ACT leader Rodney Hide says MPs are wondering what they should reveal about their past in the aftermath of the resignation of David Garrett from Parliament.
Mr Garrett revealed last week he used the identity of a dead child to fraudulently obtain a passport in 1984.
Transport Minister Steven Joyce has also admitted two careless driving convictions.
Mr Hide told Morning Report a lot of people have personal histories they can be embarrassed and ashamed of.
He said MPs and candidates across the political spectrum are being forced to think about what they should reveal.