The phrase "bounty hunter" conjures images of "wanted" posters and gunslinging cowboys hunting fugitives in the Wild West -- but the controversial profession is very much alive in modern-day America.

The industry, almost unique to the United States, came under a renewed spotlight this week as the Supreme Court refused to block a Texas law giving ordinary citizens the green light to sue anyone helping women access abortions.

Activists and politicians from street level campaigns to the White House have voiced alarm at the high court's break with 50 years of precedent in protecting nationwide access to abortion.

"In effect, (Texas) has deputized the state's citizens as bounty hunters, offering them cash prizes for civilly prosecuting their neighbors' medical procedures," Justice Sonia Sotomayor wrote in a stinging dissent.

Activists who fear the reform will metastasize saw the writing on the wall when the Texas Right to Life campaign, which has tip lines for people to anonymously report violators, said it hoped to "replicate our success across the nation."

Their concerns were confirmed when South Dakota's Republican governor Kristi Noem was among the first to suggest adopting the idea in her own state.

Bounty hunting spread across the globe from the Middle Ages but is found almost exclusively today in the United States and the Philippines.

Tristan Cabello, a historian specializing in US culture and politics, told AFP bounty hunting was a profession "deeply embedded in the American psyche... that speaks to the most conservative of US citizens."

The vast majority of bounty hunters make their living by rounding up fugitives who have skipped town in return for a share of the bail. They argue that they provide a public service at no public expense.

'Un-American'

But the Texas abortion law has reignited debate on a job that can unleash freelance law enforcement personnel whose methods are often protected from local oversight.

President Joe Biden told reporters at the White House on Friday the Texas law amounted to "vigilante" justice that "sounds ridiculous, almost un-American."

In one of the most high profile recent incidents of citizen law enforcement gone wrong in 2017, two bounty hunters died in a shootout in a Greenville, Texas car dealership, along with the fugitive they were hired to apprehend.

Neither was wearing a bullet proof vest and they had not phoned ahead to warn the business they were coming.

Reliable figures for the number of US bounty hunters are hard to come by, but the Professional Bail Agents of the United States puts the number at 15,000, while the National Association of Fugitive Recovery Agents says the industry apprehends 30,000 fugitives a year.

Bounty hunters, their relationships with police and the rules they play by are something of a gray area -- regulated by a patchwork of bewildering requirements that vary widely by state.

There is no how-to guide and most of the literature around the topic is made up of the self-promoting memoirs of its most high-profile practitioners, such as 68-year-old US reality TV star Duane "Dog the Bounty Hunter" Chapman.

Bounty hunters' rights are still defined by an 1872 Supreme Court ruling that citizens chasing fugitives are not bound by constitutional norms that apply to "state actors" such as police officers.

'Bogus civil cases'

In some states there is almost no regulation. Others allow "necessary" use of force for bounty hunters who drive imposing SUVs with blacked-out windows, armed to the teeth with guns, batons, pepper spray and handcuffs.

In a few states there is a complete ban or else requirements for various levels of experience and training, as well as background checks.

Former assistant US attorney Ken White, who litigated civil and criminal cases for decades, sees the danger of the Texas law not in its tendency to expose people to reckless bounty hunters -- but in the opportunity it presents for sanctimonious curtain-twitchers to harass their neighbors.

"Cops have a saying – 'you can beat the rap, but you can't beat the ride.' Put another way, we may not be able to convict you, but we can arrest you and detain you and put you through the system and make your life hell until your case is dismissed or you're acquitted," he said.

"It's the same spirit here -- the deluge of small harassing bogus civil cases may eventually lead to dismissals or defense verdicts, but the law is deliberately calculated to overwhelm anyone the Right thinks is connected to abortion with expensive, overwhelming litigation in which the mere process is destructive."

Michele Goodwin, of the University of California, Irvine School of Law, says the provision will be particularly hard on Black women, who are disproportionate users of abortion services.

"They already experienced... surveillance by police, disparate arrest, disparate charging, disparate sentencing," she said.

"Now this (is) an added layer to their lives and I just think how horrible to be a woman in their state who now has to look over her shoulder for yet another thing."