By Nate Raymond

A federal judge on Thursday rejected a gun rights group's challenge to an assault weapons ban the state of Connecticut adopted after an armed gunman in 2012 killed 20 children and six educators at Sandy Hook Elementary School in Newtown.

The National Association for Gun Rights filed a lawsuit in September, arguing the 2013 ban violated the right to bear arms under the U.S. Constitution's Second Amendment, citing a major U.S. Supreme Court ruling last year that expanded gun rights.

That decision, New York State Rifle & Pistol Association v. Bruen, was issued by the court's 6-3 conservative majority and held the Second Amendment protects a person's right to carry a handgun in public for self-defense.

The decision also announced a new test to assess the legality of gun restrictions, saying they must be "consistent with this nation's historical tradition of firearm regulation." NAGR said Connecticut's law failed to meet that standard.

But U.S. District Judge Janet Bond Arterton in New Haven in a 74-page ruling rejected those claims, saying the group failed to establish that assault weapons and large capacity magazines are commonly bought and used for self-defense.

Arterton, an appointee of former Democratic President Bill Clinton, cited "persuasive" evidence by the state that assault weapons are instead more often sought out for their militaristic characteristics and are often used in crimes and mass shootings.

"The Nation has a longstanding history and tradition of regulating those aspects of the weapons or manners of carry that correlate with rising firearm violence," she said, and Connecticut's ban is "consistent with that purpose."

The National Association for Gun Rights did not immediately respond to a request for comment.

Connecticut Attorney General William Tong, a Democrat whose office defended the ban in court, in a statement said the ruling "affirms that Connecticut's assault weapon and large capacity magazine bans remain on strong legal footing after the U.S. Supreme Court decision in Bruen."

(Reporting by Nate Raymond in Boston; Editing by David Gregorio)