Amazon went to trial Monday in a federal lawsuit brought by the FTC, which accuses the company of using “dark patterns” to enroll millions of customers in its $139-per-year Prime service without clear consent and making cancellations excessively difficult.

The FTC alleges that Amazon’s checkout process emphasized sign-ups while hiding crucial information in fine print and required navigating a convoluted four-page, six-click system to cancel.

The case, heard in Seattle by Judge John Chun, will use internal Amazon documents and witness testimony over a four-week trial.

Amazon argues the FTC’s claims are outdated and that the company has improved its processes, The Guardian has reported.

If the government prevails, Amazon could face significant financial penalties and be ordered to overhaul its subscription practices.