Jim Young / Reuters Gary Johnson says that his support for private prisons does not conflict with his criminal justice platform.

WASHINGTON ― Libertarian presidential nominee Gary Johnson, who campaigns for criminal justice reform, expanded private prisons as governor of New Mexico. And if he is elected president, he does not plan to end the use of these controversial facilities, he told The Huffington Post.

Private prisons can have an economic incentive to keep as many people locked up as possible at a low cost. The Obama administration doesn’t think they should be used at all.

But during Johnson’s two terms as governor of New Mexico, from 1995 to 2003, two new private prisons were built in the state, and he signed legislation that solidified standards for private facilities. Between 1999 and 2010, the number of inmates in New Mexico’s private prisons grew by more than 50 percent, according to a report by the Sentencing Project, a nonprofit that advocates for criminal justice reform. In both years, New Mexico led the nation in the proportion of inmates held in private facilities.

Johnson’s critics say his administration’s embrace of private prisons did not go as well as he claims. They say there was not sufficient oversight, new staff was less experienced, and there were a series of violent incidents, including a deadly prison riot.

“There were more, and more serious, problems at the private prisons than at the state-operated prisons,” said Jeffrey Schwartz, referring to his time consulting for the New Mexico Corrections Department in the 2000s, working on training to handle major emergencies. Among them, he cited “serious inmate violence, riots, and the assassination of at least one correctional staff officer.”

But Johnson points to his state as a success story. “I am often asked about private prisons ― and whether they create political and financial pressure to unnecessarily incarcerate drug offenders and others,” Johnson wrote in February. “When I was Governor, it simply didn’t happen.”

In an interview this week with HuffPost, Johnson elaborated that based on his experience, he believes private prisons can provide equivalent services at a lower cost.

Private prison companies in New Mexico predated Johnson, but he spurred their rise. In 1980, New Mexico had one of the worst riots in the country at a state prison, where correctional officers were taken hostage, and more than 30 inmates died. Directly afterwards, several state prisons were built, but in the 1990s and 2000s, the population outgrew state facilities, said Alex Sanchez, a spokesperson for the New Mexico Corrections Department. The way state-run prisons were built, they did not meet the space requirements of a subsequent federal consent decree, she said.

Johnson recalls that hundreds of inmates were being housed out of state because of the consent decree. “Private prisons stepped in and offered the same goods and services at about two-thirds the cost,” he said. He signed legislation, enacted in 2001, that set forth some minimum standards for these facilities, like making sure guards completed a training course approved by the secretary of corrections.

“He just thought this was the way to go — it was cost savings,” said Mark Donatelli, an attorney who served from 1980 to 1983 as director of New Mexico’s Prison Riot Defense office, which was created to represent inmates suspected of riot-related crimes. “The real mistake he made was, ironically, given his distrust of governmental competence ... he didn’t protect the state from the private entities the way he should have.”

Donatelli said Johnson replaced agency heads with less experienced people, and failed to ensure adequate oversight of the private companies. “We have operated facilities and have provided leading offender rehabilitation services in New Mexico in partnership with and under strict oversight and monitoring from the New Mexico [Department of Corrections.],” said a spokesman for the GEO Group, which operates multiple prisons in the state.

Private prisons can work if state officials provide strict oversight of contracts, said NMDC’s Sanchez. She says current New Mexico Gov. Susana Martinez’s administration is doing that. (Under her administration, the state fined major private prison companies more than $1 million for issues related to inadequate staffing and contract violations.) But Sanchez couldn’t speak on previous administrations, including Johnson’s.

A federal court would never have signed off on private prisons in New Mexico if they had offered subpar services, Johnson said. And the free market in legal services for prisoners boosts oversight, he later added. “There is an entire cadre of attorneys that look out for the civil rights of prisoners,” he said. “In many ways, they do a great job of making sure that there is no lesser goods or services.”

In 1999, almost 300 inmates were involved in a riot at the Guadalupe County Correctional Facility, which opened that year under Johnson. A group of inmates stabbed a guard to death. In the nine months before the riot, five people died in Wackenhut-run prisons in New Mexico, according to The Associated Press. The inmate homicide rate in Wackenhut’s prisons at that time was “off the charts,” at 1 for every 400 inmates, compared to 1 for every 15,000 inmates nationwide, according to a paper published by a fellow at George Soros’ Open Society Foundations.

Republican state senators blamed Johnson for helping incite the riot by threatening to move inmates back into state facilities if they continued the violence. “It’s clear private prisons aren’t working in New Mexico,” State Sen. Michael Sanchez, then-Democratic chairman of the courts and corrections committee, told the Lubbock Avalanche-Journal.

Johnson, who the year before received $5,000 collectively from two private prison companies — Wackenhut and CCA — opposed an independent study of private prisons after the riot. (He believed it was duplicative of a state review.) Johnson also told HuffPost the donations were routine, and there was “certainly no quid pro quo.”

Private prisons create an incentive for states to lock more people up. And private prison contracts in New Mexico have, in fact, stipulated a minimum number of inmates a facility had to hold. Alex Sanchez, the NMCD spokeswoman, said the current administration is trying to move away from those provisions, and regardless, “whether you put a minimum in a contract or not, New Mexico does not have enough state beds to house the population.”

But at least one major private prison company, CCA, has acknowledged that it loses with criminal justice reform. “The demand for our facilities and services could be adversely affected by the relaxation of enforcement efforts, leniency in conviction and sentencing practices or through the decriminalization of certain activities that are currently proscribed by our criminal laws,” the company wrote in 2005.

Johnson insists that his support for private prisons does not conflict with his criminal justice platform ― which includes legalizing marijuana ― because he believes private prisons will be easier to empty than public ones. But he does not plan to go as far as the Obama administration in preemptively shutting them down. Rather, he said, he will weigh costs and benefits on a case-by-case basis.

“All I have to base my experiences on is having been governor of New Mexico,” he said. “People really appreciate good stewardship of tax dollars ... is it a bargain or isn’t it?”

Sign up for the HuffPost Must Reads newsletter. Each Sunday, we will bring you the best original reporting, longform writing and breaking news from The Huffington Post and around the web, plus behind-the-scenes looks at how it’s all made. Click here to sign up!