If you’re looking for one of the reasons why the United States imprisons more people — by miles — than any other nation, you can look to the development of private prisons as a means of making some people rich. Those people spend millions of dollars to lobby elected officials to do two things: Convert government-run prisons to private prisons, and lock up more people for longer periods of time. Because that makes them even richer.

A new study by the Justice Policy Institute reaches exactly that conclusion and documents it thoroughly.

Over the past 15 years, the number of people held in all prisons in the United States has increased by 49.6 percent, while private prison populations have increased by 353.7 percent, according to recent federal statistics. Meanwhile, in 2010 alone, the Corrections Corporation of America (CCA) and the GEO Group, the two largest private prison companies, had combined revenues of $2.9 billion. According to a report released today by the Justice Policy Institute (JPI), not only have private prison companies benefitted from this increased incarceration, but they have helped fuel it. Gaming the System: How the Political Strategies of Private Prison Companies Promote Ineffective Incarceration Policies, examines how private prison companies are able to wield influence over legislators and criminal justice policy, ultimately resulting in harsher criminal justice policies and the incarceration of more people. The report notes a “triangle of influence” built on campaign contributions, lobbying and relationships with current and former elected and appointed officials. Through this strategy, private prison companies have gained access to local, state, and federal policymakers and have back-channel influence to pass legislation that puts more people behind bars, adds to private prison populations and generates tremendous profits at U.S. taxpayers’ expense.

“For-profit companies exercise their political influence to protect their market share, which in the case of corporations like GEO Group and CCA primarily means the number of people locked up behind bars,” said Tracy Velázquez, executive director of JPI. “We need to take a hard look at what the cost of this influence is, both to taxpayers and to the community as a whole, in terms of the policies being lobbied for and the outcomes for people put in private prisons. That their lobbying and political contributions is funded by taxpayers, through their profits on government contracts, makes it all the more important that people understand the role of private prisons in our political system.”

America’s obsession with locking up more and more people, while simultaneously ignoring the numerous ways that innocent people are railroaded by a corrupt and inept justice system, is not only destroying important constitutional principles, it’s also bankrupting state and local governments. It needs to be fixed.