The Ward 7 councillor has applied to court to halt the probe by integrity commissioner Janet Leiper, saying he's not getting a fair shake because news of the investigation has leaked out.
In a filing at Ontario's Divisional Court, Mammoliti complains that Leiper's decision to undertake the investigation was "put into the public domain and posted on the internet," whereas the City of Toronto Act requires her to keep her work secret until she reports her findings to city council.
The complaint appears to be a reference to media stories about the case that appeared after CBC Toronto broke the news of the investigation on Dec. 10.
"The commissioner was asked to conduct a proper investigation into this blatant breach of Councillor Mammoliti's privacy rights and her own rules requiring her to keep secret all matters that come within her knowledge in the course of her duties," Mammoliti's court filing says.
"The commissioner failed to conduct a proper investigation or to sanction those responsible for the breach."
That shows Leiper is biased, Mammoliti's application says.
Leiper's office has filed documents in court suggesting she will oppose Mammoliti's challenge, though CBC News could not immediately reach her, nor Mammoliti or his lawyer Morris Manning, for comment on Thursday afternoon.
Warned about fundraisers
Leiper has been investigating Mammoliti over a fundraiser held for him on May 22, 2013, attended by city hall lobbyists, developers, businesspeople, friends and others.
CBC reported at the time that several hundred people attended the event at the Royalton Banquet Hall in Woodbridge, just north of Toronto, with tickets costing $5,000 for a table of 10.
Two weeks before the fundraiser, Leiper herself sent out a memo to city councillors warning them about holding public fundraisers or accepting contributions.
It is a violation of the City of Toronto's code of conduct for a councillor to receive gifts or benefits connected with "the performance of his or her duties of office."
The invitation to the Mammoliti fundraiser appeared to address possible concerns, saying, "We have obtained legal [counsel] and opinion to help guide my father through this fundraising process and eliminate any possible conflicts or code of conduct issues."
Fundraising for a councillor's election campaign is only permitted during the campaign period, which began in January ahead of the municipal elections in October.
Mammoliti is also battling charges under the Municipal Elections Act that he violated campaign spending limits, accepted improper cash contributions and filed incorrect financial statements during the 2010 municipal election.