Minnesota is joining 18 other states and the District of Columbia to fight the release of blueprints online that give instructions for making guns using 3-D printers.

On Friday, Attorney General Lori Swanson joined the other states in filing a lawsuit to block online publishing of the blueprints for creating the do-it-yourself weapons, alleging it violates federal law and the U.S. Constitution.

Texas-based Defense Distributed wants to post the schematics for 3-D-printed guns, which are mostly made of plastic and are untraceable because they don't have serial numbers. The blueprints would also not require a background check to print and are easily destroyed after use. The available blueprints include guides for making guns akin to an AR-15 rifle.

"Easy online access to 3D-printed guns by criminals, terrorists, or others is a significant public safety risk," Swanson, who is one of three DFL candidates for governor in the Aug. 14 primary, said in a statement Friday. "Undetectable and untraceable 3-D guns in the wrong hands should concern everyone."

In 2015, Defense Distributed sued after the federal government forced it to remove instructions to print a 3-D weapon online. But the federal government reversed course in June, entering a settlement with the company, indicating it will alter federal rules to allow it to publish the blueprints.

On Monday, Swanson sent a letter with 20 other states to the federal government, urging it to reconsider that decision. The next day, a federal judge issued a temporary restraining order to put a hold on the release of such blueprints.

KELLY SMITH