A federal judge on Thursday upheld Colorado’s new gun-control laws that mandated background checks for all gun sales and limited the capacity of ammunition magazines to no more than 15 rounds.

U.S. District Chief Judge Marcia Krieger issued her 50-page ruling on the 2013 laws after a two-week civil trial in late March and early April in Denver.

The lawsuit was originally filed by plaintiffs including sheriffs, gun shops, outfitters and shooting ranges. Krieger ruled last year that the sheriffs could not sue the state in their official capacities but they could join the lawsuit as private citizens.

Krieger determined that the plaintiffs lacked standing in their lawsuit.

DOCUMENT: Read the judge’s decision on Colorado gun laws.

Colorado Attorney General John Suthers’ office represented defendant Gov. John Hickenlooper, who signed bills into law last year that expanded background checks and created ammunition magazine limits.

“Like Judge Krieger, the Colorado Attorney General’s Office has never asserted that the laws in question are good, wise or sound policy. As it does in all cases, the AG’s Office has fulfilled its responsibility to defend the constitutionality of the Colorado law in question,” Suthers said in a news release.

“The Attorney General’s Office fully expects the case to be appealed and looks forward to final resolution of the issues as soon as possible.”

Sen. Mary Hodge, D-Thornton, who was the Senate sponsor of the bill, praised the judge’s decision.

“This is public safety. Having people have to pause to reload saves lives,” Hodge said. “These school shooters, for the most part, did not know how to reload their weapons, so this limit on large-capacity magazines is good.”

Plaintiffs claimed the new laws impinged on their right to keep and bear arms. They promised a new legal challenge in the 10th Circuit Court.

“While we respect the judge’s ruling today, we believe that it is plainly wrong on the law and on the facts,” Weld County Sheriff John Cooke said at a Denver press conference Thursday. “John Hickenlooper knows that the (former New York City Mayor Michael) Bloomberg anti-gun laws are a failure.”

Cooke, who made headlines last year when he said he wouldn’t enforce the new gun control measures, said the laws are convoluted and impractical.

“They are still unenforceable,” he said. “And that is borne out in that there has not been one arrest on these two laws to date.”

Chad Vorthmann, executive vice president of the Colorado Farm Bureau, said the measures put an undue burden on farmers and ranchers in the state.

It’s not practical or fair, he said, to ask a ranch hand to drive hours to the nearest federally licensed firearms dealer to do the necessary background checks before being able to use his employer’s gun.

“The use of firearms on Colorado farms and ranches is integral to the success of their operations and a part of normal, everyday activities,” he said. “A sweeping ban on magazines and the unworkable system of background checks for temporary transfers and private sales of firearms places an unconstitutional burden on our members.”

Krieger’s ruling says “the Supreme Court does not equate the Second Amendment ‘right to keep and bear arms’ to guarantee an individual the ‘right to use any firearm one chooses for self-defense.'”

The Supreme Court had previously ruled that the Second Amendment did not authorize a right to keep and carry “any weapons whatsoever.” It allows legislatures to prohibit civilian use of certain weapons commonly used in military service, such as M-16 rifles.

The Second Amendment guarantees the use of weapons commonly used “at the time” for self defense.

Krieger noted that no evidence was produced at the two-week trial that indicated a person’s ability to defend himself is seriously diminished if magazines are limited to 15 rounds.

“Of the many law enforcement officials called to testify, none were able to identify a single instance in which they were involved where a single civilian fired more than 15 shots in self defense,” she noted.

Defendants argued that legislators passed laws to increase public safety following mass shootings including the Columbine High School massacre in 1999 and the Aurora movie theater shootings in 2012.

Advocates for the legislature’s tougher gun laws, including Dave Hoover, the uncle of AJ Boik, who was killed in the Aurora Theater shooting, lauded Krieger’s decision.

“As I have said repeatedly, no one is losing their rights by having to reload their gun, but with this simple measure we can reduce the number of victims killed in mass shootings,” Hoover said in a statement.

Eileen McCarron, president of Colorado Ceasefire Capitol Fund, said the lawsuit was a waste of time and resources.

“This was a politically-motivated lawsuit that has been grasping at straws from day one,” McCarron said in a statement. “These laws are reasonable protections against gun violence that many states have adopted and have repeatedly passed the test of constitutionality.”

Denver Post Staff Writer Kurtis Lee contributed to this report.

Kirk Mitchell: 303-954-1206, denverpost.com/coldcases or twitter.com/kmitchelldp