The shadow home secretary said police were right to look again at whether former minister Denis MacShane's abuse of expenses broke the law.
Yvette Cooper said the case should be re-examined in the light of "very severe condemnation" by parliament's sleaze watchdog.
The comments came after the Commons authorities insisted that damning letters from Mr MacShane to the standards commissioner could not be used against him in court.
Senior officials say they are protected by parliamentary privilege because they were collected during proceedings of the House.
More top news
Search for missing seven-year-old underway after he was reportedly abandoned in a forest by his parents as "punishment" for throwing rocks.
Shooting of a 400-pound gorilla who grabbed a four-year-old boy after he entered his enclosure sparks public outrage and prompts petition.
The 'sugar tax' outlined in Chancellor George Osborne's March budget will "hit the poor the hardest", critics claim.