Under federal civil rights law, suits can be brought when an official violates federal constitutional or statutory rights, under color of law. (42 US Code, section 1983; Bivens v. Six Unknown Agents.) If you were to violate the Fourth Amendment by making an unreasonable search or seizure, for example, you could have to pay monetary damages to the person whose rights were violated. The evidence could also be suppressed from a criminal trial, because of the exclusionary rule created by the courts to deter future violations.
On the other hand, if your interrogation of a suspect in custody failed to comply with Miranda procedures, anything the suspect told you could be suppressed at trial, but could you also be sued for having violated the suspect's Fifth Amendment rights? The recent Supreme Court decision in Chavez v. Martinez answers that question.
The Chavez Case
Oliverio Martinez, an admitted heroin user, got into a fight with officers during a narcotics investigation. He grabbed one officer's gun from its holster and pointed it at officers. He was shot, seriously wounded, and arrested.
In the hospital emergency room, police sergeant Ben Chavez questioned Martinez about the shooting. Chavez did not give a Miranda advisement or seek a waiver, presumably because everyone thought Martinez was dying and there wouldn't be any criminal trial. Although he recovered, Martinez was not prosecuted, and he later brought suit. He claimed (among other things) that the questioning violated his Fifth Amendment right against compelled self-incrimination.