Critical Race Theory is not strictly just "an idea." It is a movement (one that crosses disciplinary boundaries) with an associated body of academic work.

E.g., here's one description from Critical Race Theory: The Writings that Formed the Movement

>> This comprehensive movement in thought and life — created primarily, though not exclusively, by progressive individuals of color — compels us to confront critically the most explosive issue in America: the historical centrality and complicity of law in upholding white supremacy…

Trying to pin down exactly what CRT is can be a very difficult process. It's one that I've already grappled with a bit:

https://aninjusticemag.com/what-is-critical-race-theory-19dbaf2bf33a