The act that was designed to prevent the abuse of constitutional rights by officers who "under color of state law" deny defendants those rights is

The correct answer is the Civil Rights Act

Although many provisions of the civil rights act and similar acts that followed ban all abuse of constitutional rights by officers who separate their detainees based on color, it is a problem that still haunts the US. Things like racial profiling are still a thing and even though they are banned by the civil rights act it still happens from time to time.