The fines were handed down by the Federal Court on Friday and relate to a cluster of cases involving trespass and other unauthorised conduct on sites - including Adelaide Oval and Flinders University - in 2014.

The penalties come as Prime Minister Malcolm Turnbull prepares to go to the polls on July 2 over a bill to restore the construction union watchdog.

The Construction, Forestry, Mining and Energy Union and 15 of its officials were fined a total of $937,100 for threatening to cause work to stop, illegally entering sites and refusing to leave, the judgement shows.

In one case an official had threatened to cause a stop work at the Flinders University site if construction company Lend Lease did not allow a CFMEU flag to be flown on a crane hook.

In his judgement, Federal Court Judge Richard White described the union's compliance with industrial laws as "dismal", noting the union or its officials had been before the court 80 times for breaches from 2000 to 2013.

"On any reasonable measure that is an appalling record," Judge White wrote.

"It bespeaks an attitude by the CFMEU of ignoring, if not defying, the law and a willingness to contravene it as and when it chooses."

Judge White said he was satisfied the breaches were part of a "concerted action which involved deliberate entry onto Lend Lease building sites without providing a notice of entry."

"It means that the contraventions are to be regarded as deliberate and pre-meditated," he wrote.

Fair Work Building and Construction director Nigel Hadgkiss welcomed the decision, but said:  "I regret to say these are yet more examples of the contempt for the rule of law which exists in Australia's building and construction industry. This kind of behaviour comes at an enormous cost, affects productivity and the Australian economy."

Mr Hadgkiss said to date, the CFMEU and its officials had been penalised a total of more than $7 million as a result of court actions brought by the FWBC.

The union released a statement saying it had entered the sites to support workers in suicide prevention initiatives, help workers complete asbestos exposure forms and manage hearing concerns over rushed project deadlines.

CFMEU South Australian Secretary Mr Aaron Cartledge said the FWBC had targeted Adelaide since 2013. "We are being hounded and prosecuted over work safety stoppages including an incident at the RAH when cranes collided," he said.

"It is clear where the priorities of the Federal Government lie: with the property developers to whom they are indebted and for who they have to deliver."