You know what else is a fact? That it wouldn't have passed without Republican support. I don't say that out of any love for the Republicans. All US politicians are lower than shit in my books.

You're so trapped in this liberal vs conservative framing and it's so inaccurate. All of the politicians in the history of the USA have been Liberals (private property, autonomy of individuals, wage labor, government defense of "universal" rights, capitalism). The distinction you're making in this case is the distinction between progressivism (a liberal faction that believes it can maintain capitalism by making concessions to the masses) and a mixture of classical liberalism and "liberal conservatism" (2 liberal factions who take a hard line on limiting what the government should do to maintaining markets and personal autonomy).

But even the progressive liberals are only making those concessions, like civil rights, to stop the rioting and the only reason they are ever successful is because the social conditions call for it. There's a reason liberal democracies didn't see progressivism emerge for more than a century after liberal constitutions were written and more than 200 years after liberalism became philosophically ascendant: because liberals became afraid of successful revolution.

Progressivism is widely understood to have structurally emerged by 1890. The Paris Commune was established in 1871 and the October Revolution occurred in 1917. Progressivism in America emerged in response to an agrarian popular uprising that was contemporaneous with violent labor uprisings.

Liberalism specifically has nothing to say about these things. It was Liberalism that created these problems and it was Liberalism that used the value of private property to justify putting down these uprisings with state violence. But using violence to repress unrest creates more unrest. It's not like there weren't progressive ideas before 1890. It's just that liberal democracies didn't allow progressivism in until, after over a century of conflict with the masses, it started to look like the masses would win.

Progressivism, therefore, was used by the liberal establishment as a release valve for the tensions caused by the class war (waged on the battle fields of race, gender, ethnicity, religion, sexuality, age, ability, neurology, and others).

Yes, you are 100% right that the reason civil rights was passed is because the progressives won the day. But the progressives won because their strategy was the best strategy available for dealing with the actual crisis that was caused by black population that not only was organizing for rebellion in huge numbers that could no longer be repressed fully but we're actually winning over white people as they did so and started to make class consciousness a part of their program. Progressivism had the solution that worked for the ruling class. The ruling class benefited from resolving the crisis.

And again, how do I know this? Because that same Congress then immediately set to work to support Nixon's criminalization of drug use which the insiders in the administration knew was specifically directed at Black people and the hippies that supported them.

This is the point. The parties don't matter. They take up different positions as needed at different times. But they share a common goal: maintenance of the capitalist global empire