If you care about your freedom to modify vehicles in the United States take a read. In some ways this was a pretty big win (not a win in many others)
UNITED STATES OF AMERICA V. EZ LYNK SEZC...
"Defendants argue that Section 230 of the Communications Decency Act of 1996 immunizes Defendants from any liability under the Clean Air Act."
https://storage.courtlistener.com/recap/gov.uscourts.nysd.555597/gov.uscourts.nysd.555597.68.0.pdf