A Spokane gun dealer and an Army Reserve member are among the five Washington residents who are suing the state over I-1639, one of the strictest gun laws on the books nationally.

The owner of Sharp Shooting Indoor Range and Gun Shop, Robin Ball, and Nathaniel Casey, 19, who is in the Army Reserves, are among those who are joining the Second Amendment Foundation and the National Rifle Association in a lawsuit that says I-1639 violates the U.S. Constitution and parts of federal law.

According to the lawsuit, Ball is suing over part of the law that says dealers cannot sell rifles to non-residents.

Casey is suing based on another part of the law that would stop him from buying a firearm based on his age, according to the lawsuit. Casey already owns a semi-automatic rifle and hopes to buy others for target practice and hunting, documents state.

Initiative 1639 passed with 60 percent of the vote. It bars the sale of semi-automatic rifles to people under 21 and to people who don't live in Washington, and it requires buyers to pass an enhanced background check and prove they have taken a firearms training course.

“We are disappointed that too many Evergreen State voters were fooled into supporting this 30-page gun control scheme, despite overwhelming law enforcement opposition,” SAF Executive Vice President Alan Gottlieb said in a statement. “This initiative is an affront to the constitutional rights enshrined in the Second Amendment and the Washington state constitution, especially for young adults.”

Gottlieb said SAF is also considering other legal challenges.

“The NRA is committed to restoring the Second Amendment rights of every law-abiding Washingtonian,” said Chris W. Cox, executive director of NRA’s Institute for Legislative Action. “I-1639 violates the constitutional rights of law-abiding citizens and puts people at risk. This lawsuit is the first step in the fight to ensure that Washingtonians are free to exercise their fundamental right to self-defense.”

Supporters of I-1639 said the initiative is a major step forward for addressing factors in mass shootings and would help reduce suicide deaths by firearms and accidental shootings.

KING 5 and the Associated Press contributed to this report.

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