This week a major court case in support ofnet neutralitybegan, with a group of consumer advocates and internet trade organizations challenging the Federal Communications Commission (FCC)’s overturning of the Open Internet Order (OIO). This order, passed in 2015, is what made it illegal for internet providers to block or throttle internet speeds when accessing particular sites or platforms — i.e. it is the law that protected consumers for having to pay more for “fast lane” services, and that protected companies from having to pay extra cash to internet providers for good speeds to be available on their websites.

The case is being heard by the U.S. Court of Appeals for the District of Columbia, and it centers around whether the FCC had the right to overturn the OIO. When the OIO was passed in 2015 it was upheld by the court, and critics point out that nothing has changed since that law was put in place except the people who run the FCC. The FCC therefore may not be justified in changing the law.

“Nothing has changed since the 2015 rulemaking but the leadership of the FCC,” Lisa Hayes, general counsel for the Center of Democracy & Technology, toldGizmodo. “The FCC lacks compelling evidence justifying its 2018 order, and I expect the DC Circuit will find that the FCC’s actions were arbitrary and capricious.”

The case is being brought by a diverse group including technology companies like Mozilla and open internet advocacy groups like the Open Technology Institute and the Center for Democracy & Technology. “Today we fought for an open and free internet that puts consumers first,” Mozilla Chief Operating Officer Denelle Dixon said in a statement, according toGizmodo.“Mozilla took on this challenge because we believe the FCC needs to follow the rules like everyone else… The fight to save net neutrality is on the right side of history. Consumers deserve an open internet. And we look forward to the decision from the Court.”