In the united-states, parole board members are generally considered to be carrying out a quasi-judicial function, i.e., determining an appropriate sentence for a defendant, and therefore entitled to judicial immunity.
Judicial immunity operates as a complete bar to civil liability for monetary damages, so the board would essentially have no exposure to liability.
Judges enjoy absolute immunity from civil rights suits in order to keep the judicial decision-making process pristine. ... Just as the decision-making process of judges must be kept free from fear, so must that of parole board officials. Without this protection, there is the same danger that the decision-maker might not impartially adjudicate the often difficult cases that come before them. If parole board officials had to anticipate that each time they rejected a prisoner's application for parole, they would have to defend that decision in federal court, their already difficult task of balancing the risk involved in releasing a prisoner whose rehabilitation is uncertain against the public's right to safety would become almost impossible.
Sellars v. Procunier, 641 F.2d 1295, 1303 (9th Cir. 1981).
Parole board members whose errors proximately cause an injury to a third party would therefore likely be exposed to punishment only through criminal law or adverse employment consequences.