Following the deadly attack on a Planned Parenthood in Colorado last week, some pro-choice groups are pressing the United States government to treat anti-abortion attacks as domestic terrorism — a step that some say is important symbolically but might actually end up hurting investigations and prosecutions.

The pro-choice group NARAL asked Attorney General Loretta Lynch to direct the FBI to investigate attacks against abortion providers as domestic terrorism in a letter signed by pro-choice groups, abortion clinics and providers, women's health centers, and medical personnel, as well as a petition with more than 66,000 signatures on it.

"These attacks on clinics are part of a long history of ideologically-driven violence. They're perpetrated by an extreme minority that's committed to ruling through fear and intimidation," the petition says. "Let's call this what it is — domestic terrorism. It's time for an investigation to get to the bottom of this."

The letter was penned two days before the deadly shooting at a Planned Parenthood in Colorado Springs last week. It referenced an uptick in violent attacks on clinics around the country since the release of videos over the summer by a pro-life group that allegedly showed Planned Parenthood executives discussing the sale of aborted fetal tissue. The release of the videos prompted public outrage and calls for investigation by lawmakers, though no investigations into the video have found evidence of wrongdoing. NARAL cited three arson attacks, vandalism, and increasing threats against clinics around the country since the release of the videos in July.

On Friday, those attacks became deadly when 57-year-old Robert Lewis Dear allegedly shot and killed three people at the Planned Parenthood in Colorado. In his statements to police after the attack, Dear allegedly said "no more body parts."

"Terrorism is an action driven by ideology designed to scare a lot more people than those directly affected by the act itself," Ilyse Hogue, president of NARAL, said in a statement to VICE News. "What some seek to achieve through deceptive legislation, others have been moved to take up arms. The Colorado Springs tragedy is part of a pattern of violence through the decades seeking to end abortion through any means necessary."

The details of Friday's attack and the increase in incidents since the release of the videos has led many advocates to say that the crimes clearly fit the definition of domestic terrorism because the perpetrators have a political motivation and seek to coerce behaviors or frighten civilians. But whether the government should actually investigate the incidents as domestic terrorism is arguable, the advocates say.

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"If terrorism is violence to achieve a political end, then the details that have trickled out of Colorado Springs were absolutely domestic terrorism," said Ryan Lenz, a senior writer and online editor for the Southern Poverty Law Center (SPLC), a nonprofit legal advocacy organization.

Lenz said that anti-abortion violence fits a larger pattern of homegrown domestic terrorism that has largely been overshadowed within the Department of Justice and FBI by foreign-born, jihadist terror threats. The SPLC issued a report this summer warning of ideologically-inspired "lone wolf" terror threats and found that over the past five years, there had been one domestic terror attack every 34 days, either carried out in full or thwarted by police.

Crimes against abortion clinics and providers are currently investigated by the Department of Justice's civil rights division in a unit devoted to the Freedom of Access to Clinic Entrances Act (FACE). And those investigators, according to at least one pro-life group, are highly knowledgeable about abortion rights issues and committed to anti-abortion crimes. If the Justice Department were to order the domestic terror unit to investigate anti-abortion crimes, they may receive less attention.

"They know and understand our issue, they treat it seriously and we are not necessarily asking them to move us into the domestic terrorism division where I think our issue would get less of a priority as we compete with ISIS and al Qaeda and everyone else and compete for scarce resources," Vicki Saporta of the National Abortion Federation told VICE News.

"What is important is that clinic violence gets treated as a priority among law enforcement and at the Department of Justice, and that they have the resources necessary to thoroughly investigate crimes against abortion providers," she said.

'It makes it clear that this is an act linked to a larger political motive. Terrorism captures that.'

Saporta reiterated that she did think the attack on Friday — and many other criminal attacks against abortion providers and clinics — counted as domestic terrorism. But she did not want to see them categorically treated that way by the DOJ.

"It's absolutely important for the Justice Department, politicians, the media, and society to consider this as terrorism," David Cohen, author of the book Living in the Crosshairs: The Untold Stories of Anti-Abortion Terrorism. "But I do think there is value in having this be investigated by the Civil Rights division's FACE unit. You'd rather have people in your field investigate it."

Cohen said that it was symbolically important for Lynch and President Barack Obama to call Friday's attack domestic terrorism because the term carries weight with the American people.

"It makes it clear that this is an act linked to a larger political motive. Terrorism captures that," he said.

The use of the terrorism designation can also affect how it is investigated, with experts looking at connections among individuals and groups that plan and encourage these attacks, Cohen said. In recent years, social media has allowed would-be lone wolf attackers to collaborate across the Internet, Saporta said.

Cohen pointed out that the three deaths in Colorado on Friday accounted for the ninth, tenth, and eleventh murders of people associated with abortion since 1993, and that the number of deaths is a fraction of the total violence, targeting, and harassment carried out against providers and personnel associated with the procedure.

"I'm not opposed to labeling this as domestic terrorism in situations where it applies and we can get more resources to solve crimes and hold people accountable, but I don't think it's a magic bullet and in some cases it may not be helpful and achieve the results we want," Saporta concluded.

Lenz, of the SPLC, said that when he issued his report on lone wolf attacks this summer, no one was really paying attention to domestic terrorism. But the Colorado shooting may have changed that.

"People really are paying attention now," he said.