Although state efforts to nullify federal laws generally have been tossed out by courts, Missouri and other states have decided to try anyway. The bill’s supporters say it’s important to protect liberties in light of potential federal regulation, such as President Barack Obama’s call last year for expanded background checks and a ban on assault weapons — the bill’s impetus.

“I am proud to say that we have passed arguably one of the strongest Second Amendment protections in the country,” said sponsoring Sen. Brian Nieves, R-Washington.

The Senate voted 23-10 to send Nieves’ legislation, dubbed the “Second Amendment Preservation Act,” to the House. It would declare some federal gun laws to be null and void in Missouri. Federal agents knowingly enforcing those laws could face civil penalties and prosecution under a newly created state crime punishable by up to a year in jail and a $1,000 fine.

The legislation doesn’t state which specific federal laws would be nullified, but refers to fees, registration and tracking policies that “have a chilling effect on the purchase or ownership” of guns and ammunition by law-abiding citizens.

A similar gun rights bill passed the Legislature last year, but was vetoed by Democratic Gov. Jay Nixon. A veto override attempt failed in the Senate after the chamber’s two top Republicans voted against the measure because of concerns over several provisions. Those provisions have been removed or changed in this year’s version.

Opponents said the bill would be tossed out in court and lamented the legislation’s focus on protecting gun owners rather than fighting crime.

“This is a very unconstitutional bill and we should not be wasting our time with it,” said Sen. Jamilah Nasheed, D-St. Louis.

President Pro Tem Tom Dempsey and Majority Leader Ron Richard both voted in the favor of the legislation Thursday.

During the measure’s debate this past week, Senate Republicans found a surprising foe in the National Rifle Association. The NRA announced its opposition to the bill because of an amendment that was added to require that stolen guns be reported to police within 72 hours.

The NRA said it has consistently fought such measures and that it would lead to a de facto gun owner registry by having owners report guns to law enforcement. In response, the Senate voted Monday to strip that provision from the bill.

In a post on its website this week, the NRA thanked the Senate for removing the reporting requirement but said it was “neutral” on the overall bill.

Among the bills other provisions, designated school personnel would be allowed to carry weapons in school buildings after undergoing training. School districts would need to hold a public hearing before permitting “school protection officers” to carry concealed firearms in buildings. Staff could also choose to carry pepper spray instead of a gun.

Another provision of the bill would allow concealed gun permit holders to carry firearms openly, even in municipalities with ordinances banning open carry. It would reduce the minimum age to get a concealed weapons permit to 19 from the current age of 21. Health care professionals could also not be required to ask or document whether a patient owns a firearm.

The Senate also passed a proposed constitutional amendment Thursday that would define the right to bear arms as “unalienable” and require the state to defend against any “infringement” of that right. The proposal would also include defending one’s family with a firearm as a guaranteed constitutional right. That measure also heads to the House and, if passed, there, would go before voters in November.