A new report by In The Public Interest (ITPI) illustrates how private companies that operate prisons or services within prisons use correctional associations to gain intimate access to decision makers in government — almost entirely off the books.

Correctional associations, such as the National Sheriff’s Association or the American Correctional Association, are non-profit entities that support the private corrections industry. They host trainings, events and conferences, provide awards and scholarships and conduct public advocacy campaigns that benefit the industry. Private companies pay millions of dollars each year to attend their conferences, lead trainings and workshops, give speeches, and advertise their products and services to law enforcement officials in attendance.

To be clear, we’re not just talking about private prison companies that operate entire facilities, such as Corrections Corporation of America or the GEO Group. Correctional associations also represent companies that provide services within prisons, such as telecommunications companies, food vendors, health companies, financial services, residential re-entry programs and commissary providers.

Unlike donations and lobbying expenses, the relationships built at association events do not have to be disclosed to the public, so the true amount of influence they wield is largely unknown. To this end, ITPI notes that their report is based off only a small portion of the total amount companies contribute to associations because of what little information is available.

ITPI found that corporate sponsorships for association events can run anywhere from $2,000 to $10,000 a pop. Vendors pay around $2,000 for a booth, which ITPI explains provide a great lead generation opportunity by letting company reps chat one-on-one with officials perusing the exhibition floor. They give money towards association awards and scholarships, such as the Susan M. Hunter scholarship (organized by the Association of State Correctional Administrators), which gives about $38,000 to the college-bound child of a correctional worker. They also make general donations to support the work of associations: for instance, 86 companies gave a total of $317,000 to the National Sheriff’s Association in 2014.

That same year, sponsors, corporate partners, vendors and other entities contributed at least $3 million to the five-largest correctional associations. The American Correctional Association made at least $200,000 in sponsorships from last year’s summer conference.

This arrangement has the potential to foil the public’s best efforts to reform the criminal justice system, and to do so without a shred of transparency. Even if the public succeeds in shifting policy away from incarceration, the access to officials provided by associations gives these businesses the opportunity to market their new products and diversified services directly to the government.