Craig Thomson used more than $300,000 of Health Services Union money to pay for prostitutes and to get elected to the federal parliament.
A Federal Court judge has found the disgraced former national secretary used union credit cards for his own benefit and to the detriment of the HSU.
Thomson, formerly the Labor member for Dobell, was fined $25,000 last year for 13 counts of theft, but was acquitted of 49 fraud charges over personal transactions involving union money between 2003 and 2007.
He now faces potential financial penalties after the Fair Work Commission sued him for charging the union for political campaign materials, a $90,000 rugby league sponsorship deal and time in brothels, in breach of the Fair Work Act.
Justice Christopher Jessup said in his ruling handed down on Friday that using HSU staff member Criselee Stevens for political campaigning was the clearest example of Thomson's improprieties.
"It was no different from the manager of a construction company, for example, using the services of a carpenter employed by the company to carry out renovations on his or her domestic premises," Justice Jessup said on Friday.
Thomson did not defend himself against the commission's claim.
He left the court in March and did not return after Justice Jessup dismissed his application to have the matter thrown out on the grounds he was mentally unfit.
Thomson said at the time he was too sick to fight a legal battle and too poor to pay a fine if he lost.
He told AAP on Friday he would probably make submissions to the court when it considers what penalties and compensation orders should be made.
Thomson said the idea that there was not some coming together of the unions and the Work Choices campaign during the 2007 election was a very bizarre reading of events.
"These issues had already been dealt with and it was found I was not guilty," Thomson told AAP.
Thomson applied in February to the County Court for an order that would allow him to pay his $25,000 theft fine in instalments of $50 a month, because he had no money.
He later said family and friends would help him to pay the fine within two years after being warned he could be jailed if he could not come up with the money.
The Federal Court will hear submissions on penalties and compensation in the matter on November 9.
