The Role of the Idaho County Commissioner

Understanding the constitutional office, statutory powers, and limited authority of county commissioners in Idaho government.

Last updated: April 2, 2026 · By Jeff A. Pierson

Historical Foundations: County Government in Idaho

The role of the county commissioner in Idaho traces its authority and structure to the territorial period and was formally established in the Idaho Constitution upon statehood in 1890. Unlike state government, which derives its powers from the federal Constitution and the people, county government in Idaho exists as a creature of state legislative authority. This distinction is foundational to understanding what a county commissioner actually is and what they can actually do.

Idaho's territorial government, which grew out of the Oregon Organic Act of 1848 and the later organization of Idaho Territory, created a framework for local administration that recognized the necessity of county governance. When Idaho Territory was organized separately in 1863, it inherited and refined this structure. The territorial legislature delegated authority to counties for purposes of property administration, law enforcement, road maintenance, and other local affairs that were too distributed for the state to manage directly.

The Idaho Constitution, adopted in 1889 and ratified by the voters that year, took effect with statehood in 1890. It explicitly acknowledged county government in Article XVIII. This article does not create county powers from whole cloth; rather, it recognizes the existing counties and directs the state legislature to establish the system by which counties operate.^[1] Section 1 recognizes the counties as legal subdivisions of the state, and Section 5 directs the legislature to establish a system of county governments that is uniform throughout the state.^[2] The size of the board is set by statute rather than by the Constitution: Idaho Code 31-701 provides for a three-member board, a structure that remains unchanged today.

Throughout the late 19th and early 20th centuries, the Idaho Legislature iteratively refined county powers through the codification of what would become Idaho Code Title 31. This evolution reflects the practical reality that state government cannot administer property assessments, maintain rural roads, or provide indigent services in Boise. County commissioners serve as the state's agents in the counties, vested with specific, enumerated powers to carry out state purposes at the local level.

What a County Commissioner Is

A county commissioner is a duly elected member of the Board of County Commissioners (BOCC), the legislative and administrative governing body of a county in Idaho. The BOCC is a collegial body, not a single executive, but a three-person board that makes decisions collectively through majority vote. Idaho Code 31-701 states the rule plainly: each county must have a board of county commissioners consisting of three (3) members.^[3]

Each commissioner represents a county commissioner district. Idaho Code 31-704 requires the board, at its regular meeting in January preceding a general election, to divide the county into three districts as nearly equal in population as may be, and Idaho Code 31-702 and 34-617 set the residency requirements: a candidate must have lived in the county for one year and in the district he or she represents for ninety days before the primary election.^[4] Under Article XVIII, section 6 of the Idaho Constitution, the legislature provides for the election of county commissioners every two years, and the terms are staggered under Idaho Code 31-703, so the whole board is not replaced in a single election.

As an elected official, a county commissioner holds an office that the Idaho Constitution contemplates (Article XVIII, section 6 provides for the biennial election of county commissioners) and that the legislature defines by statute. The county itself has the power to sue and be sued, to purchase and hold land, and to make contracts necessary to exercise its powers (Idaho Code 31-604), and those powers are exercised by the board of county commissioners or by agents and officers acting under its authority or the authority of law (Idaho Code 31-602). The board also employs assistants and staff (Idaho Code 31-818), fixes the compensation of county officers and employees (Idaho Code 31-816), and exercises the other powers delegated by statute. A commissioner is, in legal terms, a "fiduciary" with respect to county funds and property, meaning commissioners hold those assets in trust for the public benefit and must exercise their powers in the public interest, not for private gain.

Commissioners are also statutory officers, meaning the Idaho Legislature has defined their specific duties, authorities, and limitations in Idaho Code. Chapter 7 of Title 31 (Idaho Code 31-701 and following) sets up the board, its chairman, clerk, meetings and ordinances, and chapter 8 (Idaho Code 31-801 and following) lists the board's powers and duties, from supervising county officers and auditing accounts to levying taxes, fixing salaries and managing county property.^[5] These statutes are not merely descriptive; they are prescriptive and limiting. Idaho Code 31-801 itself gives the board jurisdiction and power "under such limitations and restrictions as are prescribed by law," and Idaho Code 31-602 provides that the county's powers can only be exercised by the board, or by agents and officers acting under its authority or the authority of law.

Practically speaking, a county commissioner spends time in meetings of the full board, in policy deliberations, in hearings on land use and other contested matters, in public outreach, and in oversight of county staff and contractors. Many commissioners also serve on regional bodies, such as community action agencies, public health districts, or natural resources planning committees, appointed by the BOCC to represent county interests.

What a County Commissioner Is Not

Understanding what a commissioner is not proves equally important as understanding what they are. The office is defined not only by its powers but by its limits.

Not an Executive

A county commissioner is not the chief executive officer of the county. Idaho counties do not have an elected county executive or mayor in the state executive sense. The Board of Commissioners is the governing authority, but it operates collegially, all three commissioners have equal votes and equal authority to participate in decisions. No single commissioner can unilaterally direct county policy or spending. The board chair (elected by the commissioners from among themselves) presides over meetings and represents the board in formal capacity, but holds no greater substantive authority than the other commissioners.

This stands in contrast to state government, where the governor holds executive power, or to municipal governments, many of which have a mayor with executive authority separate from the city council. County government in Idaho is fundamentally legislative in character, even though it also exercises administrative functions. The board itself appropriates money, establishes policy, and oversees implementation.

Not a State Legislator

A county commissioner cannot pass laws that override or contradict Idaho state law or the U.S. Constitution. County commissioners operate under "Dillon's Rule," a doctrine of statutory interpretation that will be discussed in detail below. Under Dillon's Rule, counties possess only the powers the state has granted them, expressly or by necessary implication. They cannot legislate on matters reserved to the state. For example, a county commission cannot set a different criminal penalty for a crime, cannot establish a different tax rate structure than authorized by statute, and cannot regulate activities in ways that conflict with state policy.

County commissioners also cannot speak or vote as a "county" on matters of state or federal policy outside their delegated authority. While commissioners often advocate for county interests in state legislative or federal regulatory proceedings, they do so as representatives of the county's statutory interests, not as legislators.

Not a Judge

A county commissioner is not a judge and does not hold judicial power. Although the BOCC conducts hearings and makes determinations on matters within their administrative purview (such as land use decisions, business licensing, or budget appeals), these are administrative, not judicial, determinations. They are reviewable in the courts if a person claims the commissioners exceeded their authority or violated a statutory procedural requirement.

Judicial power in Idaho, the authority to interpret law, declare rights, and resolve disputes, is vested in the courts. A commissioner may be required to testify in court about their official actions, but the commissioner does not judge disputes between private parties or render judgments enforcing the law.

Core Statutory Duties Under Idaho Code Title 31

Idaho Code Title 31, "Counties," is the statutory framework defining county powers and duties. The following represent the principal categories of commissioner responsibility:

Property Tax Administration and the Assessor's Office

The county assessor is an elected county officer (Idaho Constitution, Article XVIII, section 6), not an appointee of the board, but the board supervises the official conduct of county officers who assess, collect, safeguard or disburse public money (Idaho Code 31-802) and sets the compensation of county officers and employees (Idaho Code 31-816).^[6] The commissioners also act on property tax exemption applications that the law routes to the board (Idaho Code 63-602), and they levy the county's property tax within limits set by state law (Idaho Code 31-811 and 63-802). The BOCC approves the annual county budget, which includes assessment costs and property tax administration expenses.

Roads, Bridges, and Transportation Infrastructure

Idaho Code 31-805 directs the board to lay out, maintain, control and manage public roads, turnpikes, ferries and bridges within the county and to levy such tax for them as the law authorizes, except inside the boundaries of a highway district formed under Title 40.^[7] In practice this means setting road standards, accepting or declining road dedications, maintaining the county road network, and overseeing the road department budget and operations. Many counties employ a road and bridge superintendent to run the department. County roads, unlike state highways, are maintained primarily through county property taxes and the state's distribution of highway funds to local governments.

Indigent Services and Public Welfare

Chapters 34 and 35 of Title 31 of the Idaho Code give county commissioners responsibility for indigent assistance and for county hospital and medical assistance matters. For example, Idaho Code 31-3401 directs boards of county commissioners, within the limits the law prescribes, to evaluate the need for and provide nonmedical assistance to indigent persons in a temporary situation only when no alternatives exist, and to adopt policies and procedures by resolution. Boards also approve the budgets for these programs. This responsibility reflects the historical reality that local communities bear primary knowledge of their residents' circumstances and needs.

Planning, Zoning, and Land Use Regulation

Idaho Code Title 67 grants counties the authority to adopt comprehensive plans and zoning ordinances, subject to constitutional and statutory limits. The BOCC does not necessarily serve as the planning and zoning commission (many counties delegate that to a separate planning and zoning commission), but commissioners adopt the comprehensive plan, enact the zoning ordinance, and hear appeals of planning and zoning decisions made by the commission. Planning and zoning authority is not unfettered; it must be exercised consistently with the county's comprehensive plan, and any restrictions on property use must substantially advance legitimate public interests.

Law Enforcement and Sheriff Relations

The county sheriff is an elected constitutional officer separate from the BOCC, but commissioners work closely with the sheriff. Commissioners approve the sheriff's budget, may authorize special law enforcement services, and coordinate with the sheriff on public safety matters. The commissioners do not direct the sheriff's investigative or enforcement decisions (which would violate the sheriff's constitutional independence), but they ensure the county provides adequate resources for law enforcement.

Elections Administration

The board has defined election duties. Under Idaho Code 31-804 the board of county commissioners must establish, abolish and change election precincts and canvass all election returns, and must provide the poll lists, poll books, blank returns and other supplies needed to hold elections in the county. The county clerk, who is elected, runs the elections themselves, and the board approves the budget for election administration. Title 34 of the Idaho Code governs elections generally.

Public Buildings and Facilities

Commissioners are custodians of county buildings and facilities. They approve capital improvement budgets, lease agreements, and maintenance contracts for courthouses, sheriff offices, road shops, fairgrounds, and other county property. The board also typically oversees the county's insurance, risk management, and property maintenance.

Budget and Financial Oversight

Perhaps the most consequential duty of the BOCC is the adoption of the county budget. Idaho Code 31-1601 and following (the County Budget Law) set the process: the county auditor, as budget officer, prepares the suggested budget, and the commissioners tentatively and then finally appropriate to each office and department after a public hearing. The county's fiscal year begins on October 1. This is where commissioners exercise their greatest discretionary authority: within the constraints of available revenue and statutory mandates, they decide what services to provide and at what level.

The Oath of Office: Constitutional Boundary

Every county commissioner, before assuming office, must take and subscribe the official oath prescribed by Idaho Code § 59-401, which provides in part that the oath is taken before the officer enters upon the duties of the office:^[8]

This oath is not ceremonial. It is a legal obligation with constitutional weight. The oath contains three essential elements:

First, support for the U.S. Constitution: A commissioner takes an oath to support, to uphold, to honor, and to defend, the Constitution of the United States. This means that no state law, no county ordinance, no federal program, and no political pressure can justify a commissioner violating or disregarding the Constitution. If a state law or federal mandate conflicts with the Constitution, the Constitution prevails, and a commissioner bound by oath cannot execute an unconstitutional directive.

Second, support for the Idaho Constitution: A commissioner similarly swears to support the Idaho Constitution. This includes Idaho's Declaration of Rights, which protects property rights, free speech, and due process. Many controversies at the county level involve tensions between state mandates and constitutional protections. An example: a state statute might direct counties to enforce a particular regulation, but if that enforcement violates the due process rights protected by the Idaho Constitution, a commissioner's oath requires choosing the Constitution.

Third, faithful discharge of duties: A commissioner swears to "faithfully discharge the duties" of the office. This language binds the commissioner to exercise the powers granted by statute and to exercise them for their lawful purpose, the benefit of the county and its residents. "Faithfully" implies good faith, impartiality, and dedication to the public interest. It prohibits corruption, nepotism, abuse of power, and exercise of authority for private purposes.

Term, Election, and Vacancy Procedures

The Idaho Constitution (Article XVIII, section 6) and Idaho Code 31-702 through 31-705 and 34-617 set the framework for electing county commissioners.^[9]

Terms and Staggered Elections

Commissioners are elected at the general election and serve staggered terms under Idaho Code 31-703, so that the entire board is not up for election at once. The board elects one of its members as chairman at its first regular meeting on the second Monday of January after the election (Idaho Code 31-705). This staggered system ensures continuity on the board and prevents total turnover. If all three seats were contested simultaneously, a single election could replace the entire governing body, potentially disrupting ongoing programs and relationships.

Because the Constitution calls for commissioners to be elected every two years while the board has three seats, the seats are not all filled in the same cycle: in one general election one seat is filled and in the next, two. The exact term lengths and rotation among districts are set in Idaho Code 31-703. Whatever the cycle, at least one commissioner with prior experience is normally on the board after any election, which promotes institutional knowledge and policy continuity.

Partisan Elections

County commissioners are elected in partisan elections. Candidates run with a party affiliation (Republican, Democrat, or third-party designation), and voters choose their party's nominee in a primary election, with the general election determining the winner. This is distinct from nonpartisan local elections used in some states. Idaho's partisan county elections reflect the state's historical practice and the recognition that political parties have played a role in county governance.

Vacancy and Succession

If a commissioner dies, resigns, or is removed from office before the end of the term, a vacancy occurs (Idaho Code 59-901). Unlike most county offices, a vacancy on the board of county commissioners is not filled by the remaining commissioners. Idaho Code 59-906 provides that vacancies in county offices are filled by the commissioners, "except that of the county commissioners (who shall be appointed by the governor)," and Idaho Code 59-905 likewise provides that vacancies in the membership of the board are filled by the governor. Idaho Code 31-817 confirms that the board's power to fill county vacancies by appointment does not extend to members of the county board.^[10] The statute does not state a term-length rule for a commissioner appointee in this passage, so the length of an appointee's service should be confirmed with the county clerk or prosecuting attorney before relying on it.

Appointment by the governor keeps the board at full strength without the delay and expense of a special election, and it avoids the problem of a two-member board deciding who its third member will be. When only two commissioners remain, they still form a quorum, because a majority of the three-member board is two (Idaho Code 31-706).

The Three-Commissioner Structure

The three-commissioner board is not an arbitrary number. It reflects historical practice and serves important structural purposes that protect good governance and prevent tyranny.

Historical and Constitutional Grounding

The three-commissioner structure appears to originate in colonial and territorial American practice, where county governing bodies typically consisted of three to five members. Idaho's territorial laws of 1868 already provided for a board of three (the history notes to Idaho Code 31-701 cite 1868 session laws), and the present statute continues that structure. Nothing in Article XVIII of the Idaho Constitution fixes the number; the size of the board is a statutory choice that the legislature has kept unchanged for well over a century.

The number three carries inherent advantages: it avoids deadlock (an even number of commissioners could split on every issue), it distributes authority among multiple people (preventing one commissioner from dominating), and it permits a quorum of two, because a majority of the board constitutes a quorum (Idaho Code 31-706). The board can function even if one commissioner is temporarily absent.

Quorum and Decision-Making

Idaho Code 31-706 provides that a majority of the board constitutes a quorum, which on a three-member board is two commissioners.^[11] The same section provides that the chairman presides at all meetings and, if the chairman is absent or unable to act, the members present must by order select one of their number to act as chairman temporarily. A commissioner acting alone cannot bind the county; the board acts as a body at a meeting that complies with the open meeting law, and the statute requires that the vote of each member on any question on which there is a division be recorded in the minutes (Idaho Code 31-708 sets out the clerk's duties, including recording those votes).

A quorum of two means that commissioners must deliberate and persuade each other. A commissioner cannot unilaterally move forward on major decisions. If Commissioner A and Commissioner C disagree with Commissioner B, Commissioner B cannot act alone. This structure forces consensus-building and prevents any individual from usurping authority.

However, a board of three in which two commissioners agree can make county policy and spend county funds, even over the objection of the third. The third commissioner is not powerless: that commissioner can speak, have a dissenting vote recorded (Idaho Code 31-708(3)), appeal to the public, and prepare for the next election. Some actions require more than a simple majority. For example, an emergency expenditure under Idaho Code 31-1608 and an appropriation from the general reserve under Idaho Code 31-1605 each require the unanimous vote of the commissioners. This reflects the democratic principle that the majority governs, and it also illustrates the importance of elections: if voters believe the majority commissioners are acting wrongly, voters can elect different commissioners.

The Structure as Deliberative Safeguard

Political science and historical experience both suggest that three-member bodies promote deliberation and restraint better than single executives or larger councils. A single executive with autonomous authority tends toward aggressive use of power, the temptation to act unilaterally is strong. A very large body (ten or more members) can descend into gridlock or operate through hidden power structures where a few members dominate.

Three commissioners must listen to each other. The board chair cannot ram through a decision; the chair must persuade at least one other commissioner. Dissenting commissioners can voice objections, appeal to the public, and position themselves for the next election if they believe the majority is acting wrongly. Over time, the three-commissioner structure has proven to be a practical and effective design for county governance.

Dillon's Rule: The Principle of Limited Authority

One of the most important principles defining the authority of county commissioners is known as "Dillon's Rule." Named after John F. Dillon, a 19th-century jurist who set out the principle in his treatise on municipal corporations, Dillon's Rule holds that local governments possess only those powers expressly granted by the state, those necessarily implied from the grant, and those essential to their declared purposes.^[12] Any fair, reasonable doubt about whether a power is granted is resolved against the local government. The Idaho Supreme Court has described this rule as the prevailing view in Idaho for municipal corporations. Idaho also has a constitutional grant that complements it: Article XII, section 2 allows any county or city to make and enforce, within its limits, local police, sanitary and other regulations that are not in conflict with its charter or with the general laws.

The Principle Stated

Dillon's Rule is often summarized as follows: A local government has authority to exercise only those powers that are (1) expressly granted by statute, (2) necessarily implied by the express grant, or (3) essential to the declared objects and purposes of the local government. Any doubt is resolved in favor of the state and against the local government.

In Idaho, the Supreme Court has recognized Dillon's Rule as the prevailing view, and it has long held that a local government possesses and exercises only the powers expressly or impliedly granted to it. At the same time, Article XII, section 2 of the Constitution authorizes local police regulations that do not conflict with general law, and Idaho Code 31-714 lets the board pass ordinances not repugnant to law that are necessary to carry out the powers and duties the law confers and to provide for the safety, health and welfare of the county. Where state law is silent or conflicts, the county must be able to point to a constitutional or statutory source for what it does.

Why Dillon's Rule?

Dillon's Rule reflects a fundamental principle of American federalism and constitutional law: sovereignty and inherent authority belong to the people and the state; local governments are created by the state and possess only delegated authority. A county is not a sovereign entity with inherent rights to govern. It is a subdivision of the state, created by state law to carry out state purposes locally.

This principle prevents counties from exceeding their legitimate scope and helps ensure that state law is uniform across the state unless the Legislature specifically permits local variation. It also prevents counties from accumulating powers through judicial interpretation or common law, which would undermine legislative control.

Dillon's Rule in Practice

Examples of Dillon's Rule in practice help illustrate its operation. Suppose a county commission passes an ordinance regulating the design of new commercial buildings within the county. The Legislature has granted counties planning and zoning authority under Idaho Code Title 67. The commissioners believe that design standards will promote aesthetics and community character. However, property owners challenge the ordinance, arguing it exceeds the authority granted in the statute.

A court applying Dillon's Rule would examine the zoning statute carefully. If the statute grants authority to regulate land use and building standards, the ordinance might be upheld as a reasonable exercise of the granted authority. But if the statute is silent on design standards, the court would interpret that silence against the county. The county did not receive explicit or necessarily implied authority to regulate design, so the ordinance exceeds the county's delegated powers and is void.

Another example: suppose a county commission imposes a local sales tax without state authorization. The Legislature has granted counties authority to levy property taxes within statutory limits (Idaho Code 31-811 and 63-802) and certain other specific charges, but no general authority to impose a local sales tax; Idaho's sales tax is a state tax administered by the State Tax Commission (Idaho Code Title 63, chapter 36). Under Dillon's Rule, the county cannot do it, regardless of whether commissioners believe it is necessary or fair. Only the state Legislature can authorize a local sales tax.

Constitutional Tension: Dillon's Rule and Federal Mandates

A significant constitutional tension arises when the federal government, through statute or regulation, requires counties to carry out federal policies. Dillon's Rule is a doctrine of state law; it does not directly constrain federal authority. However, when federal requirements conflict with state law or state constitutional limitations on county authority, the tension becomes acute.

Conclusion: The Commissioner as Constitutional Trustee

A county commissioner in Idaho is a constitutional officer, elected by the people, bound by oath to the Constitution, and vested with limited but important authority to govern the county on behalf of the state. The commissioner is not an executive with autonomous power, not a legislator with state-wide authority, and not a judge with interpretive power. Instead, the commissioner is a member of a three-person collegial body, required to deliberate with colleagues, constrained by statutory limits (Dillon's Rule), and accountable to the voters for faithful discharge of duties.

The structure of county government, three commissioners, staggered elections, quorum requirements, limited authority, reflects centuries of constitutional practice and the lessons of experience about how to govern locally without accumulating tyrannical power. A commissioner who understands the office as a constitutional trust, who takes the oath seriously, who respects Dillon's Rule, and who deliberates in good faith with colleagues is fulfilling the purpose of the office: to serve the county and its residents within the bounds of law.

Pictures, Numbers and Infographics

Every acre of Idaho sits inside one of 44 counties, and each county is run by a three-member board. Most of those boards serve small places: the Census count below shows how many Idaho counties have fewer than 10,000 people, and how many other local governments now share the same ground.

By the numbers

• 44: county governments in Idaho, the same number the Census of Governments has counted in every count since 1942. U.S. Census Bureau, Census of Governments, 2022
• 3: members on every board of county commissioners, whatever the county's size. Idaho Code section 31-701
• 15 of 44: Idaho counties with fewer than 10,000 residents. Together they held 83,934 people. One county, with 511,931 residents, is in the 500,000-or-more group. U.S. Census Bureau, Census of Governments, 2022
• 1,168: local governments in Idaho in 2022: 44 counties, 199 cities, 118 independent school districts and 807 special districts. U.S. Census Bureau, Census of Governments, 2022
• Every 2 years: how often the Idaho Constitution has the legislature provide for electing county commissioners. The sheriff, assessor, coroner and treasurer are elected every four years. Idaho Constitution, Article XVIII, section 6
• 2nd Monday: of each month: the regular meeting day for every board, at the county seat, unless the board sets more frequent meetings by ordinance. Idaho Code section 31-710
• $682,355,670: property tax levied by the 44 counties for 2025, the budgets these boards adopt. Idaho State Tax Commission, Annual Report, 2026