Justice Jeffrey Oliphant also found there is no credible evidence Mulroney performed any services for the $300,000 lobbyist Karlheinz Schreiber gave him, Canwest News Service reports.
However, he said there is also no evidence the cash Mulroney received came from Airbus commissions paid to one of Schreiber's companies.
Oliphant's findings were made public in a four-volume report that stops short of accusing the former prime minister of lying under oath at a 1996 hearing into his relationship with Schreiber.
He dismissed as "patently absurd" Mulroney's assertion that he did not disclose the relationship because he was not asked the "correct question" by the lawyer interrogating him.
In a statement following the report's release Monday, Mulroney said he regrets his conduct gave rise to suspicions about the propriety of his business affairs as a private citizen.