What were Plessy and his lawyers risking by taking their case to the Supreme Court?

Upon being charged for boarding a "whites only" train car, Plessy's lawyers defended him by arguing that the law was unconstitutional. He lost at trial, and his conviction was affirmed on his appeal to the Louisiana Supreme Court. Plessy then appealed to the U.S. Supreme Court, which agreed to hear his case.

this isn't a question and if you're going to list things be kind and use commas.

a case involving the laws of a single state.