The Montana Code Annotated, usually shortened to MCA, is the official compilation of every statute passed by the Montana Legislature, organized by subject and available free online. It covers criminal penalties, family law, property rules, business formation, taxation, and most other areas of state law. The Legislature updates it after each session, and the Code Commissioner assigns every new law its permanent place in the collection.1Montana Code Annotated. Table of Contents – MCA
How the Code Is Organized
The MCA uses a four-level hierarchy: title, chapter, part, and section. Titles sit at the top and represent broad subject areas. The code contains over 50 individual titles, numbered up to Title 90, with some numbers reserved or skipped for future use. Titles span subjects from taxation (Title 15) to criminal law (Title 45), property (Title 70), and environmental protection (Title 75).1Montana Code Annotated. Table of Contents – MCA
Each title breaks into chapters that narrow the focus. Within chapters, related provisions are grouped into parts, and parts contain individual sections with the actual text of the law. This layering lets you start with a general subject and drill down to the exact rule you need without reading thousands of unrelated pages.
How to Read a Montana Code Citation
Montana code citations look like a short string of numbers separated by hyphens, and the format tracks the hierarchy. In a citation like 1-1-501, the first number is the title, the second is the chapter, and the final group encodes both the part and section. That example reads as Title 1, Chapter 1, Part 5, Section 1.2Montana Judicial Branch. A Guide to Montana Legal Research
So a citation like 45-5-201 means Title 45 (Crimes), Chapter 5 (Offenses Against the Person), Part 2 (Assault), Section 1. Once you recognize the pattern, you can jump straight to the right place in the online code or a print index without hunting through a table of contents.
Where to Find the Montana Code Annotated
The Montana Legislature hosts the current digital version of the MCA on its official website at no charge. After a bill is signed by the governor or passed over a veto, it gets incorporated into the online code, which is refreshed after each legislative session.3Montana Legislature. Statutes You can browse by title or search by keyword.
The Legislature also runs a separate tool called the Legislative Automated Workflow System, or LAWS, which tracks bill history, hearing schedules, vote records, fiscal notes, and the full text of bills while they move through the process. LAWS is the right tool during an active session, when you want to follow a bill in real time rather than wait for its final placement in the code.
For in-person research, the State Law Library of Montana is located in the Joseph P. Mazurek Justice Building at 215 N. Sanders in Helena and is open to the public on weekdays.4Montana Judicial Branch. State Law Library of Montana The library carries the MCA, administrative rules, attorney general opinions, and other legal materials, and staff can help with navigating volumes or locating historical amendments. Some county law libraries across the state also keep copies for public use.
Subject Areas Residents Look Up Most
A handful of titles come up far more often than others for the average Montanan.
Title 45 covers criminal law, defining offenses and their penalties. Chapters within Title 45 address offenses against people (assault, stalking, endangerment) and offenses against property (theft, arson, criminal mischief).5Justia. Montana Code Title 45 – Crimes, Chapter 5, Part 2 Penalties range from fines to prison time depending on the severity of the offense.
Title 40 governs family law, including marriage, divorce (called “dissolution” in Montana), child custody, and child support enforcement. Chapters within this title also cover mediation requirements and the Uniform Child Custody Jurisdiction and Enforcement Act, which matters when custody disputes cross state lines.6Montana Code Annotated. Montana Code Annotated – Title 40 Family Law
Title 70 handles property rights, including the Residential Landlord and Tenant Act, security deposit rules, real property transfers, and eviction procedures (called “forcible entry and detainer” in the code).7Montana Code Annotated. Montana Code Annotated 2025 – Title 70 Property
Title 35 provides the framework for business entities, covering corporations, LLCs, partnerships, nonprofit corporations, and cooperative associations. This is where you find requirements for formation filings, registered agents, and annual reporting obligations.8Montana Code Annotated. Montana Code Annotated Title 35 – Corporations, Partnerships, And Associations
Other titles that regularly matter include Title 15 (taxation), Title 61 (motor vehicles), Title 39 (labor law), and Title 33 (insurance). The code’s table of contents is the fastest way to identify which title governs a particular issue.
When a New Law Actually Takes Effect
Most new statutes don’t take effect the moment the governor signs them, which matters if you’re trying to confirm whether a change in the law has kicked in yet. Under MCA 1-2-201, the default effective date for any statute adopted after January 1, 1981, is October 1 following passage and approval. Statutes that appropriate public funds default to July 1 instead. In either case, the Legislature can specify a different effective date in the bill itself, and some bills include emergency clauses that make them effective immediately upon approval.9Montana State Legislature. Montana Code Annotated 1-2-201 – Statutes – Effective Date
The Montana Constitution requires the Legislature to meet in regular session every odd-numbered year, for no more than 90 legislative days.10Montana State Legislature. Montana Constitution Article V Section 6 – Sessions The governor can also call special sessions for specific purposes, though these are relatively rare. All laws passed in a single session are first published in order of passage in a volume called the Laws of Montana, commonly referred to as Session Laws, before the Code Commissioner’s staff assigns each new permanent provision a section number and incorporates it into the MCA.11Montana State Legislature. How to Read a Bill
The MCA Isn’t the Whole Picture: Administrative Rules
When the Legislature passes a statute, it often directs a state agency to fill in the operational details through administrative rules. Those rules carry the force of law, and unlike statutes that only change during legislative sessions, administrative rules can be adopted or revised throughout the year.12Montana State Legislature. Overview of Administrative Rulemaking and Rule Review
The complete collection is called the Administrative Rules of Montana (ARM). Before an agency can adopt, change, or repeal a rule, it must publish a proposal notice citing the statute that grants it rulemaking authority, describe the change, and explain why it’s needed. The public then gets a comment period before the rule can be finalized. These notices appear in the Montana Administrative Register (MAR), which the Secretary of State’s office publishes twice a month.13Montana Secretary of State. ARM and MAR Administrative Rules Services
If you’re researching a regulated area like professional licensing, environmental permits, or utility rates, check the ARM alongside the MCA. The statute gives the broad authority; the administrative rule tells you the specific procedures, forms, and deadlines.
What “Annotated” Adds
The word “annotated” in the code’s name means it includes more than just the raw text of each statute. The MCA provides the legislative history of each section, cross-references to related provisions, editorial notes, and citations to state and federal court decisions interpreting the law. If you want to know how courts have applied a particular statute, the annotations under that section point you toward the relevant cases.
The MCA also includes several foundational documents beyond the statutes themselves: the Montana Constitution, the U.S. Constitution and its amendments, the Declaration of Independence, Montana’s Enabling Act, and the rules of civil, criminal, and appellate procedure adopted by the Montana Supreme Court. The Montana Constitution sits above everything in the MCA; no statute or administrative rule can conflict with it, so if a statute looks like it collides with a constitutional right, that’s a flag worth taking seriously before relying on the statute.