Sheriffs in Colorado filed a federal lawsuit Friday ahead of the implementation of new state gun laws that broaden background checks and limit the size of ammunition magazines, saying that the bills would be nearly impossible to enforce.

The laws "severely restrict citizens' rights to own, use, manufacture, sell, or transfer firearms and firearms accessories," the sheriffs said in their complaint in the U.S. district court.

"This is a bipartisan effort," said Larimer County Sheriff Justin Smith. "These are Democratic sheriffs and Republican sheriffs who came together."

The National Shooting Sports Foundation, magazine-maker Magpul Industries, and the Colorado State Shooting Association were among other groups that filed suit alongside sheriffs against the laws, which are set to take effect June 1.

Scarred by some of the deadliest incidents of gun violence in American history, including last year's Aurora movie theater shooting and the 1999 shooting at Columbine High School, the state's gun control bills gained national attention as various states and the federal government debated new gun restrictions.

The sheriffs said in the filing that their ability to enforce the laws, particularly the ban on magazines that hold more than 15 rounds, will be constrained by other concerns.

"The Sheriffs have limited resources and limited public funds to spend on investigations," they said in the court documents. "They cannot expend those resources to conduct investigations that would be necessary to monitor compliance with the new magazine restrictions. No documentation has ever been required for the retail or private purchase of magazines, making it a practical impossibility for the Sheriffs to determine whether one of the many magazines already in existence was obtained after the effective date."

The sheriffs also said that Coloradans would find it difficult to comply with expanded background check regulations that would require transfers between individuals to be conducted through a federally licensed firearms dealer. That's because many licensed firearms dealers in the state "are unwilling to conduct the transfer under such conditions," they argued.

Colorado Attorney General John Suthers released a statement on Friday saying that his office would pursue court rulings on the gun legislation “as expeditiously as possible.”

“Colorado citizens, and law-abiding gun owners in particular, deserve such clarification,” Suthers said in the statement.

The state has 64 sheriffs, said Chris Olson, executive director of the County Sheriffs of Colorado. The lawsuit is being brought forth “by individual sheriffs” and his organization is not a party to the suit, he said.

At least one lawman has said that deciding which laws are constitutional should stay out of the hands of Colorado’s sheriffs.

Arapahoe County Sheriff Grayson Robinson, whose county includes the Aurora movie theater where 12 people were killed last year, released a statement in January pushing back against sheriffs who said they would not enforce new gun laws.

“Public safety professionals serving in the executive branch do not have the constitutional authority, responsibility, and in most case, the credentials to determine the constitutionality of any issue,” Robinson said in the statement. “Law enforcement officials should leave it to the courts to decide whether a law is constitutional or not.”

Robinson identified himself as a supporter of Second Amendment rights in the statement, and said he would like to see better mental health services and stricter penalties for people who commit gun crimes.

Related:

• Colorado Gov. Hickenlooper signs landmark gun-control bills
• Colorado sheriff blasts colleagues over refusal to enforce gun laws
• After Newtown, states slow to embrace new gun laws

The judge who will hear the capital murder case against accused Colorado theater gunman James Holmes said Thursday he will hold a hearing on the constitutionality of Colorado's insanity defense law in death penalty cases.

Arapahoe County District Judge Carlos Samour Jr. ruled that he will consider a defense motion that argues the statute is unconstitutional because it prevents  Holmes from calling his own mental-health experts at sentencing if he refuses to cooperate with court-appointed psychiatrists.

This decision comes just three days after Holmes' lawyers said they wanted to change his not guilty plea to not guilty by reason of insanity.

Holmes appeared in court Monday with a thick, brown beard. He sat wordlessly and stared straight ahead as his attorney, Daniel King, told the judge that the defense has a mental illness diagnosis for the 25-year-old former medical student at University of Colorado-Denver.

Prosecutors said last month that they would seek the death penalty for Holmes.

Earlier in the case, defenders had asked then-presiding Judge William Sylvester to declare Colorado's insanity defense law unconstitutional because it compels a defendant to work with court-appointed psychiatrists, which may violate one's right against self-incrimination. Prosecutors objected to these claims.

But Samour, who was assigned the case last month, ordered both sides to present arguments on the issue at a hearing next week.

Court documents read:

"The Court orders the parties to confer... on the defendant's contention that [the insanity defense law] is unconstitutional to the extent it prevents him from calling any psychiatrist or other expert witness to provide evidence of his mental condition at the sentencing hearing if he fails to cooperate with psychiatrists and other personnel conducting the Court-ordered sanity examination."

Twelve people were killed and 58 wounded on July 20, 2012, at a midnight showing of the movie “The Dark Knight Rises” in the Denver suburb of Aurora. Holmes has been charged with 166 counts of murder, attempted murder, and other offenses in connection with the massacre.

Related:

Accused Aurora theater shooter requests plea change

Johnny Hanson / AP

Barry Bailey and his wife Judy, of DeRidder, La., walk out hand-in-hand, after having their 1873 Winchester shotgun appraised at the NRA's Antiques Guns and Gold Showcase during the National Rifle Association's 142 Annual Meetings and Exhibits at the George R. Brown Convention Center in Houston. The 2013 NRA Annual Meetings and Exhibits runs from Friday through Sunday, with more than 70,000 people expected to attend.

HOUSTON – A thousand miles couldn’t keep them away.

Bob Kittredge, 73, and his wife drove from Port St. Lucie, Fla., this week to attend the National Rifle Association’s annual convention. They are just two of the more than 70,000 people expected at the event, which opens Friday and runs through Sunday.

“We meet a lot of people who think the same way we do,” Kittredge said.

It will be a nine-acre gun show in the middle of a national gun fight.

About 550 exhibitors have packed the sprawling George R. Brown Convention Center in downtown Houston.

"NRA members vote and their friends vote,” said Drew Kelley, who said he’s been an NRA member for most of his life. “That is what's driving all this."

Kelley works for ProMag Industries, a firearm magazine manufacturer in the Los Angeles area that’s been in business for about 35 years and employs about 150 people.

Kelley said he values the Second Amendment – and that recent attempts at tighter gun control measures are misguided.

“The whole idea was to keep people who should not have guns from acquiring them,” he said. “But the people who they're talking about don't go through the normal commercial processes anyway.”

'Stand and Fight'

 After the mass shootings in Aurora, Colo., and Newtown, Conn., the NRA’s opponents seemed to have momentum. But two weeks ago, a bipartisan compromise on expanded background checks for commercial gun sales was shot down in the Senate.

“We don't mistake battles for wars,” outgoing NRA president David Keene told NBC News. “It was a victory in a battle, but the war continues.”

Keene’s two-year term concludes at the convention. Starting Monday, Keene will be replaced as president by Alabama attorney Jim Porter, although Executive Vice President Wayne LaPierre will continue to be the organization’s main spokesman.

In his letter to convention attendees, LaPierre writes: “For months, our enemies have laid siege to the rights we cherish…But we are proving to be stronger than ever.”

This year’s convention slogan: “Stand and Fight.”

“My concern as an NRA member is that any legislation needs to be targeted towards criminals and not law-abiding people,” said Bill Dermody, who works for Savage Arms, the Massachusetts-based firearm manufacturer that is one of the largest in the country and one of the convention’s 550 exhibitors.

On Friday afternoon, scheduled speakers include Sarah Palin, Texas Gov. Rick Perry, Texas Sen. Ted Cruz, Louisiana Gov. Bobby Jindal and former Pennsylvania Sen. Rick Santorum.

The opposition

 Outside the convention hall, several gun control advocates are planning to protest. At least one relative of a Newtown victim will attend. Another group plans to set up across the street and read 4,000 names of victims of gun violence.

The NRA’s opponents are launching a coordinated effort ahead of the 2014 midterm elections. The groups claim they finally have the financial clout to challenge the NRA thanks to Super PACs backed by New York Mayor Michael Bloomberg and former Arizona congresswoman Gabrielle Giffords.

"We're simply losing too many loved ones to this epidemic and it's time for change," said Ladd Everitt, the spokesman for the Coalition to Stop Gun Violence. “And if people won't do the right thing, then we are going to work tirelessly to make sure their political careers come to an end.”

Gun control advocates argue that the NRA’s leadership cares more about the gun industry – and profit – than the rights of gun owners.

“I think the NRA leadership is wildly out of step with their own members on the issue of expanding background checks,” Everitt said.

Portland Police Bureau

Kevin Purfield, 45, of Portland, Oregon.

PORTLAND, Oregon - An Oregon man was arrested on Wednesday on suspicion of harassing family members of some of the 12 people slain by a gunman who opened fire on moviegoers inside a Colorado theater last summer, police said.

Kevin Michael Purfield, 45, of Oregon, is accused of contacting relatives of the Aurora, Colorado, victims through telephone calls, email and social media networks, police in Portland and Aurora said.

Portland Police Bureau Sergeant Pete Simpson said he had little information about Purfield's background aside from the fact that law enforcement had previous contact with the suspect, including at least one "mental health call."

Slideshow: Shooting at Batman screening in Aurora, Colo.

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Twelve people were killed and 58 injured when a gunman opened fire during the premiere of a Batman movie.

Launch slideshow

A spokesman for the Aurora police, Frank Fania, said Purfield's contacts with victims' families numbered in the dozens, and started with the suspect offering unfounded conspiracies about the massacre.

"In the beginning it was this conspiracy theory stuff," Fania said, "then it went away from the conspiracy theory into personally attacking the families, calling them names and hoping bad things would happen to them."

A Facebook page and blog identified as belonging to Purfield stated, for example, that some coffins of the Aurora victims were empty. There were also discussions of the September 11, 2001, attacks on America and the December 2012 mass shooting that left 20 children and six adults slain at Sandy Hook Elementary School in Newtown, Connecticut.

The suspect in the Aurora shooting rampage, James Holmes, 25, is charged with multiple counts of first-degree murder and attempted murder, and prosecutors announced last week that they would seek the death penalty if he were convicted.

The July 20 shooting spree, unleashed during a midnight showing of the Batman film "The Dark Knight Rises," also left 58 people wounded.

Aurora police contacted the Portland Police Bureau in February, seeking assistance in an investigation into the harassment reported by victims' families.

Purfield was arrested without incident and booked on five misdemeanor charges of telephonic harassment and one count of stalking, police said.

Prosecutors in the Holmes case recently raised the issue in connection with arguments over newly unsealed court records, citing "ongoing harassment" of victims and witnesses and "potential intimidation by individuals who have no relationship to the case."

Victims' identities were made public in some case documents, and the names of the dead, their families and survivors of the shooting have appeared in numerous media accounts of the tragedy and its aftermath.

Purfield was jailed in lieu of $10,000 bond and was slated to be arraigned in Multnomah County Court on April 11. The case would be tried in Portland. 

Pool / Reuters file

Accused Aurora theater shooting suspect James Holmes listens at his arraignment in Centennial, Colorado in this file photo taken March 12, 2013.

A University of Colorado at Denver psychiatrist treating movie-theater massacre defendant James Holmes warned police of "homicidal statements" Holmes made one month before the Aurora, Colo., attack, according to a search warrant unsealed Thursday.

Dr. Lynn Fenton reported to University of Denver Police in June that Holmes posed a threat to the public through violent comments he made to her, according to the newly released court documents.

She also advised police that Holmes had stopped seeing her but had begun threatening her via text messages.

Holmes is accused of killing 12 and injuring 70 in a gruesome attack on a movie theater in Aurora, Colo. on July 20.

According to the document, University of Denver Police alerted Aurora, Colo. authorities of the received threat shortly after the attack.

The search warrant also reveals that on July 12, shortly before the shooting, Holmes sent Fenton a notebook that contained burned $20 bills.

The documents were released late Thursday after a judge ruled the arrest and search warrant affidavits could be unsealed following a request from various media organizations. 

District Judge Carlos Samour said the information had largely already been made public during court proceedings. But both prosecuting and defense attorneys objected.  

Holmes attorney's said they worried the release could hurt their client's chances at a fair trial. Prosecutors expressed concerns about the privacy of victims and witnesses.

Samour took over the case earlier this week after previous Judge William Sylvester stepped down, unable to commit the time necessary to preside over a death penalty case.  

On Monday, prosecutors announced they would seek the death penalty, despite the defense's offer to have Holmes plead guilty and serve a life sentence. 

Prosecutors said Monday that they will seek the death penalty for James Holmes, the man accused of gunning down 12 people and wounding 70 at a Batman movie last summer in Colorado.

George Brauchler, the district attorney for Arapahoe County, said he made the decision after speaking with more than 800 victims and family members.

“It’s my determination and my intention that in this case, for James Eagan Holmes, justice is death,” he said at a hearing.

Brauchler had already rejected an offer from the defense to let Holmes plead guilty and serve a life sentence.

Judge William Sylvester of the Colorado circuit court entered a plea of not guilty for Holmes last month after his lawyers said they were not ready to plead. The judge left the door open for lawyers to mount an insanity defense.

Sylvester on Monday set Holmes’ trial for Feb. 3, 2014, and said it would last about four months. He handed the case to a new judge, Carlos Samour. The trial had originally been scheduled to begin in August.

“This is not an ordinary case. We ask the judge not to rush,” one of Holmes’ lawyers, Tamara Brady, said, answering prosecution claims that the defense has tried to delay the legal process. “This is the most important matter the court will ever hear.”

The two sides in the case fought in public last week. After the defense made its offer, Brauchler said in a filing that Holmes’ lawyers were only trying to generate sympathy for their client.

The only conclusion, the prosecutor wrote, “is that the defendant knows he is guilty, the defense attorneys know he is guilty and that both of them know that he was not criminally insane.”

Brauchler wrote an Op-Ed in The Denver Post over the weekend defending the death penalty. Colorado legislators have considered banning it. He did not name Holmes but wrote of capital punishment as an important tool of justice.

“Repealing the death penalty would result in acts similar to those in Newtown, Conn., or the acts of Tim McVeigh being punished no differently than a single murder of one gang member by another,” the prosecutor wrote. “Each murder after the first would be a freebie.”

Injection is the method for capital punishment in Colorado. The state has executed only one inmate since the Supreme Court reinstated the death penalty in the United States in 1976, according to the Death Penalty Information Center. That execution was in 1997.

R.J. Sangosti / Pool

Aurora theater shooting suspect James Holmes listens at his arraignment March 12.

Holmes’ lawyers have said that jailers determined he was a danger to himself and needed a mental evaluation, and that he was held for several days in a psychiatric ward, sometimes in restraints.

He surrendered to police within minutes of the July 12 shooting rampage at a midnight screening of the movie “The Dark Knight Rises” in Aurora, Colo., a suburb of Denver.

At his first court appearance, Holmes had stark, red-orange hair and wore a blank stare. He has since appeared more stable and natural-looking. He showed up in court last month with a bushy beard.

The hearing Monday was set to begin at 11 a.m. EDT. Legal observers have pointed out that the two sides could still reach a plea deal later, even as prosecutors seek to put Holmes to death.

NBC News producer John Boxley, Reuters and The Associated Press contributed to this report.

This story was originally published on Mon Apr 1, 2013 8:17 AM EDT

A judge entered a plea of not guilty Tuesday for James Holmes, the man accused of massacring 12 people at a Batman movie last summer, and scheduled a one-month trial beginning in August.

Judge William Sylvester of Colorado circuit court entered the plea after lawyers for Holmes said they were not ready to plead. The judge left the door open for lawyers to mount an insanity defense later.

RJ Sangosti / Denver Post / Pool via AP

James Holmes, Aurora theater shooting suspect, sits in the courtroom during his arraignment in Centennial, Colo., on Tuesday, March 12, 2013.

Holmes walked into the courtroom in Centennial, Colo., and locked eyes with his parents, who were sitting in the second row of the courtroom. He did not show any emotion.

The judge set an Aug. 5 trial date. Prosecutors will announce by April 1 whether they will seek the death penalty.

The judge ruled Monday that Holmes must waive medical confidentiality and agree to be drugged for a psychiatric exam if he wants to claim that he is not guilty by reason of insanity. His lawyers had claimed that those provisions violated his constitutional rights.

Sylvester ruled that Holmes would have to turn over the names, addresses and medical reports of any doctor or psychologist who has treated him for a psychiatric condition.

The defense claimed in papers revealed last week that Holmes was hospitalized for several days last fall and required restraints.

Twelve people were killed and 70 injured in the July 20, 2012, shooting rampage at a midnight screening of the movie “The Dark Knight Rises” in Aurora, Colo. Holmes surrendered to police within minutes of the attack.

At his first court appearances, Holmes had reddish-orange hair and a blank stare. At subsequent hearings, his hair has been more natural-looking and his demeanor more stable. He appeared Tuesday with a bushy beard.

Colorado lawmakers on Monday advanced a package of legislation aimed at reducing gun violence in the state.

The Associated Press and Reuters contributed to this report.

This story was originally published on Tue Mar 12, 2013 10:23 AM EDT