Second Amendment right groups sued the state of California Monday over the new law banning the sale of firearms to people under the age of 21.

The groups, the Calguns Foundation and Firearms Policy Coalition, argued in a lawsuit filed in San Diego on behalf of individual gun owners that those 18 and over are adults and have a right to purchase a firearm.

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“Once individuals turn eighteen, they are adults in the eyes of the law,” said John W. Dillon, the Carlsbad attorney representing the groups, the Los Angeles Times reported.

“Law-abiding adults are entitled to fully exercise all of their fundamental rights, including their Second Amendment right to keep and bear arms for all lawful purposes, not just hunting or sport.”

“Law-abiding adults are entitled to fully exercise all of their fundamental rights, including their Second Amendment right to keep and bear arms for all lawful purposes, not just hunting or sport.” — John W. Dillon

The lawsuit stems from a new law that was introduced by State Sen. Anthony Portantino, D-LA., last year following the Parkland high school shooting where the 19-year-old gunman took the lives of 17 people.

But the lawsuit argues that any adult who isn’t a convicted felon or mentally ill should be allowed to use the Second Amendment.

“The Second Amendment is not a second-class right and adults over the age of eighteen but under twenty-one are not second-class people,” said Brandon Combs, president of the Firearms Policy Coalition, according to the Times.

“The Second Amendment is not a second-class right and adults over the age of eighteen but under twenty-one are not second-class people.” — Brandon Combs

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The legal challenge was also filed the same day another divisive gun law came into effect which mandates background checks for everyone buying ammunition in the state to ensure the person isn’t convicted felon.

The gun rights groups say the state is unprepared to roll out such law and told the newspaper that the system has problems “worse than even we anticipated.”

“The process takes about a half hour per customer instead of the promised 2 minutes,” said Chuck Michel, whose office filed a legal challenge this year in a bid to overturn the law.

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“We are collecting and will be presenting these facts, and the related constitutional issues, to the court and asking for an injunction to block this useless infringement of law abiding gun owners’ rights,” said Michel.