One's rights under the law of the land.
In the US, the term is associated with a 60's movement to ensure the equal rights of all citizens, white and non-white. Though often associated with that narrow time slice, this movement has been going on, in various forms, since the 19th Century.
There was also a Civil Rights movement in Ulster in 1968-69, started by Catholics inspired by the works of Martin Luther King; its demise led to "The Troubles".