Washington state’s new voter-approved gun-control measure violates citizens’ Second Amendment right to bear arms, gun-rights advocates including the National Rifle Association asserted in a lawsuit filed Thursday.

The law known as Initiative 1639 was approved by 60 percent of voters in last week’s election. It calls for buyers of semi-automatic rifles to be age 21 or older, pass an enhanced background check and show proof of having taken a firearms training course, Q13 FOX of Seattle reported.

But those objecting to the new law include the NRA and the Bellevue, Wash.-based Second Amendment Foundation, who filed their lawsuit in U.S. District Court in Seattle.

“We are disappointed that too many voters were fooled into supporting this 30-page gun control scheme, despite overwhelming law enforcement opposition," Second Amendment Foundation Executive Vice President Alan M. Gottlieb said in a statement. "This measure will have a chilling effect on the exercise of the constitutional rights of honest citizens while having no impact on criminals, and we will not let it go unchallenged.”

"This measure will have a chilling effect on the exercise of the constitutional rights of honest citizens while having no impact on criminals, and we will not let it go unchallenged.”

— Alan M. Gottlieb, executive vice president, Second Amendment Foundation

Among the plaintiffs are a member of the U.S. Army Reserve and a competitive-sport shooter, both under age 21, the Seattle Times reported.

The lawsuit also argues that aspects of the new law appear to require regulation of interstate commerce – which falls under the purview of the federal government, not the state.

The gun-rights advocates tried earlier this year to keep the proposal off the ballot, the Times reported.

GUN OWNERS GROUP VOWS TO SUE AFTER WASHINGTON STATE PASSES TOUGH NEW REGULATIONS

Tallman Trask, a spokesman for the Alliance for Gun Responsibility, told the Times that the lawsuit amounted to a “Hail Mary” last-ditch effort by supporters of the Second Amendment.

“We always expected the NRA or the gun lobby in general, to sue and try to stop I-1639,” Trask told the Times, because they “can’t stop it at the ballot box.”

In an email, Tara Lee, a spokeswoman for

The office of Democratic Gov. Jay Inslee was still reviewing the lawsuit, spokeswoman Tara Lee told Q13 FOX.

"We intend to defend the will of the voters in this state," she wrote.