The dispute is over the Montana Firearms Freedom Act, which was adopted by lawmakers and signed into law by the governor in the state. It specifies that weapons and ammunition made, sold and kept in the state are exempt from federal licensing and other regulations.According to the 10th Amendment, the federal government doesn't have the right to regulate commerce that occurs purely within a state's borders. Of course the Fed's are arguing otherwise.
The federal government is arguing that the Commerce Clause allows federal agencies to impose any requirement they choose on those weapons, and the dispute is pending at the 9th U.S. Circuit Court of Appeals now.
As part of those arguments a long list of states, individuals and organizations have filed amicus briefs with the appellate court, and one, from the Weapons Collectors Society in Montana points out that Montana became a state in the union under a legal compact, and at the time, "It was the understanding of the parties that the United States Constitution would not be construed by the federal government to deny or disparage the rights reserved by the people of Montana and by the State, including the right to regulate and engage in the intrastate manufacture and sale of guns and ammunition.
"Congress' commerce powers are broad; however, such powers are not unlimited," the brief explained. "The Commerce Clause itself imposes constraints on Congress' authority to regulate wholly intrastate activities. The MFFA is a law that allows Montana to regulate exclusively what the United States Supreme Court … would describe as a 'local matter' – firearm production and trade conducted within Montana's borders," the brief argues.Thus, it's not within the purview of the federal government, and therefore, not within the realm of Congress' legislative responsibility.
Hat Tip: NewsAlert