Democracy Watch says Lobbying Commissioner Karen Shepherd is investigating a complaint about a political fundraiser hosted by Apotex chairman Barry Sherman in August 2015 that featured Prime Minister Justin Trudeau and Liberal candidate Michael Levitt, now an MP.
Democracy Watch co-founder Duff Conacher says pharmaceutical giant Apotex was registered to lobby MPs at the time the fundraiser was held at Sherman's home and should not have been helping raise money for the Liberals.
Sherman himself was a lobbyist under the company registration.
The firm now is registered to lobby Trudeau's office, although ethics rules prohibit such work for five years after a lobbyist helps raise money for a politician or party.
The advocacy group complained to Shepherd in November about the $1,500-a-ticket fundraiser.
Conacher's organization is also urging Shepherd to recuse herself from this investigation because the Liberal government renewed her contract for six months in December.
Conacher says the rules are clear.
"Federal lobbying ethics rules say it is illegal for a lobbyist to do anything that puts any federal politician or candidate in even the appearance of a conflict of interest and a person crosses that line if they help in any way with a fundraising event involving a politician while they or their business or organization is lobbying the politician," he said in a statement Wednesday.
"Federal lobbyist ethics rules also say it is illegal for anyone to help a party, candidate or politician with fundraising or campaigning and then be involved in lobbying them any time within the following five years."
Trudeau and the Liberals have been under fire for months over cash-for-access events.
Shepherd is already investigating other fundraisers.
The fundraisers saw donors pay as much as $1,500 to rub shoulders with Trudeau or one of his cabinet ministers away from the public spotlight. Critics say the practice undermines government transparency and accountability.
They say it also flies in the face of Trudeau's own ethical rules for his government, which stipulate that "there should be no preferential access or appearance of preferential access" in exchange for political donations.
Last month, the Liberals promised to introduce legislation that would require greater public reporting about the political fundraisers, force cabinet ministers, party leaders and leadership candidates to publicly advertise the fundraisers in advance, and release a report some time after the fact about details of the event.
The legislation would also require the events to take place in publicly available spaces, a move designed to address concerns about well-heeled donors bending the ears of cabinet ministers in private homes.
Conacher said this move doesn't go far enough.
"The only way to stop the unethical and undemocratic influence of big money in federal politics is to stop big money donations."