In a letter to Conflict of Interest and Ethics Commissioner Mario Dion, a public watchdog group has asked for an expanded investigation into the SNC-Lavalin affair.

Democracy Watch has called for a probe the role of every person named by former justice minister and attorney general Jody Wilson-Raybould in her testimony to the Commons justice committee last week.

The group also reiterated its call for Dion to delegate this review to a provincial ethics commissioner with no ties to the federal Liberals.

That's because, according to Democracy Watch, Dion was chosen by the Trudeau cabinet in a "secretive" process that did not involve consultation with opposition parties. 

The group's cofounder, Duff Conacher, maintained in the letter that this violated the Parliament of Canada Act.

Moreover, he noted, Dion came under fire in his previous job as the integrity commissioner on eight occasions, including for consistently failing to name government officials found guilty of wrongdoing.

The former auditor general, Michael Ferguson, concluded there was "gross mismanagement" in Dion's former office's handling of two cases involving whistle-blowers.

Today's letter to Dion makes the argument that under the Conflict of Interest Act, SNC-Lavalin meets the definition of a "person".

In coming to that conclusion, Conacher cited a 2010 ruling by the previous ethics commissioner, Mary Dawson. At the time, she found that the Interpretation Act provides that a "person" includes a "corporation" unless a contrary interpretation appears in legislation.

"In the absence of any other definition in the Conflict of Interest Act, the definition in the Interpretation Act applies," Dawson wrote in 2010.

In today's letter, Conacher also stated that SNC-Lavalin had a private interest in avoiding prosecution.

Therefore, he argued that any public office holder's attempt to influence Wilson-Raybould's position regarding the prosecution of SNC-Lavalin constituted an attempt to "use his or her position as a public officer holder to seek to influence a decision of another person as to...improperly further another person's private interest".

That, he suggested, is a clear violation of section 9 of the Conflict of Interest Act.

"Democracy Watch also requests an investigation into whether anyone used secret information they learned from their position in government in an effort to influence the Attorney General (which would violate section 8 of the Act)," Conacher wrote, "and whether anyone from SNC-Lavalin has a relationship with anyone in the government that would cause them to give them preferential treatment by trying to influence the Attorney General (which would violate section 7 of the Act)."