The Trump administration's plan to reconsider privately run prisons faces a web of complications amid litigation and allegations the industry cuts corners at the expense of security.

Last month, Attorney General Jeff Sessions rescinded an Obama-era memo directing the Bureau of Prisons to start phasing out the use of private prisons.

Supporters maintain the private model is cheaper and more efficient, and Sessions' directive was an apparent nod to that argument. The industry also has pushed back strongly on claims it skimps on rehabilitative programs like job training.

“We do not believe in cost-cutting for profit's sake as critics like the ACLU contend,” Pablo Paez, vice president of corporate relations for top private prison provider GEO Group, told Fox News. “Instead we believe in running an efficient operation that provides adequate staffing and relies on state of the art technology for monitoring, communication, health care and rehabilitation programs.”

But critics point to a Justice Department audit that found private facilities have more safety and security problems than government-run ones. In moving to phase out these operations, the Obama administration also cited the decline in the federal prison population.

Critics also allege some for-profit prison providers enjoy a cozy relationship with Sessions.

“Jeff Sessions is a private prison enthusiast,” said Donald Cohen, executive director of In the Public Interest, a left-leaning Washington non-profit.

A private prison – also known as a for-profit prison – is run by a third party that is contracted by a government agency.

In the U.S., there are two leading private prison providers – GEO Group and CoreCivic (formerly known as Corrections Corp. of America). Both companies donated heavily to Republicans during the 2016 election cycle and both have seen their share prices double in value since President Trump’s White House win.

GEO maintains it has never taken a position or been an advocate for or against any criminal justice, sentencing or immigration policy. Paez says the company’s “contributions should not be construed as an endorsement of all policies or positions adopted by any individual candidate.”

Private prisons were virtually non-existent in the 1980s but shot up more than 1,600 percent between 1990 and 2009. As incarceration rates continued to climb, the private prison industry grew with it – expanding at exponential rates.

As the Obama administration began to put a damper on that growth, Democratic presidential contenders Hillary Clinton and Sen. Bernie Sanders both vowed to keep the Obama directive during last year's campaign.

Shares of GEO and CoreCivic (formerly Corrections Corporation of America) tumbled.

But with Trump’s surprise November win and Sessions in place as the country’s top cop, the private prison industry has recouped its losses and is currently on track for a substantial windfall.

The market capitalization of GEO has roughly doubled to $3.7 billion; CoreCivic’s market capitalization is more than $4 billion.

In the Public Interest said the policy change didn’t come as a total shock.

Sessions backs a no-holds-barred approach to going after drug and violent crime offenders. In a Feb. 21 memo, the former Alabama Republican senator said Obama’s efforts to end privatization had “impaired” the U.S. Bureau of Prison’s “ability to meet the future needs of the federal correctional system.”

Sessions' comments indicate he expects a significant rise in people being incarcerated, though the number of federal prisoners has been on the decline since 2013. It is now at its lowest rate in a decade. According to the Federal Bureau of Prisons, there are 189,041 total federal inmates. Of those, 11 percent or 21,359 federal inmates are held in private prisons.

Trump's illegal immigration crackdown, though, could represent one area where the administration hopes to employ private facilities.

Nina DiSalvo, executive director of Towards Justice, a Colorado-based nonprofit that represents low-wage workers, told The Washington Post that Trump’s pledge to deport 2 million to 3 million undocumented immigrants creates an environment where for-profit prisons could make millions detaining and deporting those who cross the border illegally.

Cohen believes Sessions’ motives run deeper.

“As Alabama’s attorney general, Sessions green-lighted their use in the state, and shortly after the Obama Justice Department’s original announcement, GEO Group ... hired two former Sessions aides as lobbyists,” Cohen said.

The Justice Department did not respond to multiple requests for comment from Fox News.

Private prison companies operating in the United States handle facilities and inmates for the federal Bureau of Prisons, the U.S. Marshals Service and the Department of Homeland Security – which includes detainees from Immigration and Customs Enforcement.

With government contracts worth millions of dollars on the line, groups like the American Civil Liberties Union argue that a profit motive introduces perverse incentives into the job of running prisons.

The less a prison spends per inmate on things like health care, upkeep and security, the more it can make monetarily, they say.

“Certain private prison companies employ shrewd tactics to obtain more and more government contracts to incarcerate prisoners,” the 2011 ACLU report “Banking on Bondage: Private Prisons and Mass Incarceration,” claimed. The report said tactics include: “use of questionable financial incentives; benefitting from the ‘revolving door’ between public and private corrections; extensive lobbying; lavish campaign contributions; and efforts to control information.”

Safety concerns also have been cited. After a well-documented 2010 escape from an Arizona private prison, an Arizona Department of Corrections audit revealed that prison staff hired by Management & Training Corp. were "fairly green," "not proficient with weapons," and habitually ignored sounding alarms.

Around the same time, at least 28 riots were documented in private prisons in Arizona, as well as more than 200 other "disturbances" involving dozens of inmates.

Earlier this month, a federal judge green-lighted a 2014 lawsuit filed against GEO to continue as a class-action lawsuit. It’s the first time a class-action lawsuit accusing a private prison company of violating federal anti-slavery laws has been allowed to move forward.

The suit centers on conditions at the 1,500-bed prison at the Denver Contract Detention Facility. The prison, owned and operated by GEO Group, is accused of using tens of thousands of immigrants detained by ICE to work for $1 a day – or for free.

GEO maintains it did nothing wrong.

“We have consistently, strongly refuted these allegations, and we intend to continue to vigorously defend our company against these claims,” Paez told Fox News. “The volunteer work program at immigration facilities as well as the wage rates and standards associated with the program are set by the Federal government. Our facilities, including the Aurora, Colo. Facility are highly rated and provide high-quality services in safe, secure and humane residential environments pursuant to the federal government’s national standards.”

In addition to allegations of forced labor at private prisons, there have also been accusations of collusion.

In 2011, for example, Pennsylvania Judge Mark Ciavarella was convicted of racketeering, racketeering conspiracy and money laundering conspiracy in connection with payments received from a private prison developer.