Senate Majority Leader, Sen. Tom McGillvray, R- Billings, has joined two other Montana State Senators, Sen. Greg Hertz, R-Polson and former Sen. Keith Regier, R-Kalispell, in filing a lawsuit challenging the lawfulness of SB 542, which was one of Montana’s major tax reform bills passed by the 2025 State Legislature.

Filed in the Gallatin County District Court, plaintiffs in the case essentially claim that the bill is unconstitutional. It violates at several aspects of Article V, Section 3 of the Montana Constitution.

Sen. McGillvray explained that SB 542 was introduced by Sen. Wylie Galt, R-Martinsdale, as a tax freeze. As it passed through the legislative process it was amended so greatly that its purpose became unrecognizable as to its original intent, which made it unconstitutional according to the three Senators.

“It became a monstrosity,” said McGillvray.

It was introduced to freeze property taxes at their 2024 level, but it became a bill that revised and shifted taxes, provided multiple appropriations and even suspended local city charters, explained McGillvray. ”It became a bill with three different subjects and with multiple appropriations” – all of which stands in violation of the State Constitution, which requires that each bill must deal with only one subject .

Further – it was changed so drastically that the bill’s title no longer reflected its original purpose of freezing taxes at 2024 levels. The Montana Constitution also requires that a bill’s title must accurately reflect its subject matter. The Constitution restricts changing a bill so much that it is changed from its original intent.

Introducing bills dealing with several subjects – “that’s what they do in Congress,” said McGillvray, “They make a big bill with multiple appropriations, that picks winners and losers. They buy enough votes to get it passed. That is what we try to prohibit, so each legislator can look at a single subject.”

“Montanans pride ourselves that our Legislature debates each policy idea on its own merits, with genuine public participation. We’re not Washington, D.C., where massive bills get cobbled together behind closed doors and shoved down legislators’ throats as ‘must pass’ legislation,” continued McGillvray, “ Senate Bill 542 was Washington DC-style corruption. We warned our colleagues on the floor that SB 542 violated Article V, Section 11. We voted to send it to conference committee to fix the constitutional violations. The conference committee ignored the constitutional issues and passed it out with no changes – a sham hearing.”

Violation to Article V section 11: 1-5:

 (1) Change the original purpose of a bill (11) (1) a bill shall not be so altered or amended on it passage through the legislature as to change its original purpose.”  It changed from a 2 page 7 line amendment to freeze property taxes to raise property taxes permanently for some and lower it for others. 

2. . Single subject: (11) (3) (4) each bill except for a general appropriations bill … “shall contain only one subject, clearly expressed in its title.

SB 542 changed from one subject with the purpose to freeze property taxes to at least 3 subjects;

1.  Appropriate 92 million for the $400.00 rebate

2. Revise property tax rates in multiple property tax classes. It raised some rates, lowered others permanently, shifting the reduction from the 80% to the 10%, with the other 10% remaining about the same.

3. It suspended local charters and provided an additional appropriation to cover lost revenue for four years. (This is likely another constitutional violation) of local government powers. 

Senate Bill 542 is to be implemented in two phases. The first phase applied to tax year 2025 and the second phase will generate tax bills that will be issued in November 2026.