Remember Prohibition? That wasn't lifted because people wrote to their Congresspeople, but otherwise respected the law and followed it. It was lifted because it was widely disrespected, and a huge black market for alcohol was created, along with a lot of brutal violence. Same goes for civil rights for black people in the 1960s. Same goes for civil rights for gay people (like legalizing gay sex, previously criminalized). People committed the crimes and got caught, it went through the justice system somehow, and either a law was passed or the Supreme Court rule on it. It took a Supreme Court case to nullify the anti-gay-sex laws when some people in Texas were prosecuted for it and it got appealed up to the supremes as a privacy/freedom issue.