CHEYENNE, Wyo. — The attorneys general for Utah and Wyoming said Wednesday that their states and South Dakota will join a federal lawsuit pending in Montana in which pro-gun groups are seeking to protect that state’s sovereign right to regulate guns. The attorneys general confirmed that they plan to file a “friend of the court” brief in the Montana case this week, and that South Dakota also plans to join them. All the states involved have enacted “firearms freedom” laws that seek to exempt guns made and sold within their borders from federal regulation. Montana was the first state to pass such a law. The federal Bureau of Alcohol, Tobacco, Firearms and Explosives sparked the current legal fight when it wrote to all licensed gun dealers in the state last year telling them they were still bound by federal gun regulations. The Montana Shooting Sports Association and others then sued the federal government, which argued that Montana lacked authority to exempt guns from national gun control laws. The various states claim that as long as the guns aren’t involved in interstate commerce, the federal government should have no say over them. Gary Marbut, head of the MSSA and himself a plaintiff in the lawsuit, said Wednesday the group was pleased that the attorneys general of the other states saw the merit of the case and wanted to be involved. Marbut said Montana’s law was followed by similar laws enacted in Tennessee, Utah, Wyoming, South Dakota and Arizona. A similar bill is sitting on the governor’s desk in Idaho. Marbut said similar laws have been introduced in 21 other states. Republican Utah Attorney General Mark Shurtleff of Utah said Wednesday that his state’s law is similar to the Montana statute. “It’s just nice to show the court a number of other states are concerned and this issue goes beyond Montana,” Shurtleff said. Utah Gov. Gary Herbert, a Republican, signed the Utah bill into law this year after Shurtleff assured him it could be defended at a minimal cost because the issue would be decided in Montana. Wyoming Attorney General Bruce Salzburg confirmed his office would join with Utah. That state’s Democratic governor, Dave Freudenthal, said Wednesday his state is getting involved because Montana’s law also is similar to Wyoming’s and the pending case relates to the legal issues that Wyoming faces. “It’s legislation similar to what we just passed,” Freudenthal said. “So the (brief) that’s coming from Utah, as I understand it, is very narrow on the question of the reach of the federal government in the context of the 10th Amendment and the Commerce Clause.” Efforts to reach South Dakota officials for comment were unsuccessful. Alexander Kenneth Haas, a lawyer with the U.S. Department of Justice in Washington, declined to comment Wednesday. Marbut said many gun and states rights groups will also be signing on. “Hopefully it will impress the court that this is a serious deal,” Marbut said. “It’s very exciting and encouraging that so many others understand the merit of the concept.” A trial is currently scheduled for December in the Montana case. The federal government has filed a motion to dismiss, and the court is awaiting a response from the MSSA and other interveners on that point. Patrick Fox, the local counsel for Utah and the other states, said he expects the Montana case will ultimately serve as the nationwide legal vehicle to resolve the question of the limits of the federal government’s authority over guns manufactured and sold in a single state. “Montana’s on the cutting edge of this jurisprudence, and it’s important in two respects,” the Montana-based lawyer said, adding that it was a states’ rights issue, as well as a gun rights issue that deals with the Constitution’s Second Amendment right to own firearms. “So it’s an important issue in two regards that are very hot-button issues in this day and age,” he said. Gouras reported from Helena. Associated Press Writer Brock Vergakis in Salt Lake City also contributed to this report.