Senator Mike Duffy returns to Parliament Hill in Ottawa on Monday, May 2, 2016. (Photo: Sean Kilpatrick/CP)Ministry spokesman Brendan Crawley says the Crown decided there is no legal basis for an appeal. Duffy was acquitted in April on 31 criminal charges, including fraud, breach of trust and bribery, stemming from his Senate expenses. At the time, Duffy's trial judge was critical of the Crown's case, saying that prosecutors failed to prove beyond a reasonable doubt that Duffy acted unlawfully. The Crown withdrew charges of fraud and breach of trust last week against retired Liberal senator Mac Harb and the RCMP announced it wouldn't pursue criminal charges against Sen. Pamela Wallin. That leaves Patrick Brazeau as the only senator still facing criminal prosecution over his housing expenses.