Turnitin, long a staple of colleges' plagiarism prevention efforts, sells the leading AI detector combating generative AI's threat to academic integrity.

Almost three-quarters of California community colleges now use Turnitin, as does nearly the entire California State University system.

This year alone, the Cal State system is paying over a million dollars for Turnitin's detectors.

An investigation by CalMatters and The Markup revealed institutions willing to renew Turnitin subscriptions year after year, despite the cost, faulty technology, and concerns about privacy and intellectual property raised by the company's ever-expanding student paper database.

Turnitin executives did not respond to requests for comment about their business practices, but the company's technology offers only a shadow of accurate detection.

It highlights matching text, whether properly cited or not.

It flags sentences that mirror AI's writing style, whether a student used AI inappropriately or not.

Turnitin licenses this technology to colleges while receiving perpetual royalty-free rights to student work.

The company has used these rights to amass 1.9 billion student papers into a database that help bolster its market position and build new products.

Some students report being wrongly accused of cheating because of Turnitin's faulty detectors.

Others worry they could be next and take elaborate steps to protect themselves from blame.

Meanwhile, the cost to colleges adds up.

The Los Angeles Community College District is paying $265,000 for this year's Turnitin license loan.

Purchase records show Turnitin offers lower prices to some California colleges and not others.

While Cal State Northridge is paying $3.19 per student this year UC Irvine is paying $3.86 for the same technology.

For CalMatters, I'm Tara Garcia Mathewson.