Gyms, travel agents and car hire companies have been put on notice that they face being sued over contracts that rip off consumers.
The warning follows a review by the Australian Competition and Consumer Commission (ACCC) into unfair contracts offered by companies.
Industries targeted by the review were chosen due to a high number of complaints from consumers hiring cars, joining gyms or booking travel.
The ACCC believed some contracts offered by such companies caused a significant imbalance to the detriment of consumers.
ACCC chairman Rod Sims said that in most cases, the businesses under review chose to make changes removing problematic terms from their standard form contracts.
However some had not cooperated with the ACCC during the review or chose not to change their standard form contracts to address problematic terms.
"The ACCC is considering whether court action is warranted against businesses to deal with specific provisions still in use which it considers may operate unfairly," Mr Sims said in a speech to the Consumer Congress in Sydney on Friday.
Now that the report had been released, the ACCC plans to focus on enforcement such as court action, rather than working with companies to comply, he said.
That could involve court orders to refund money or vary contract terms.
Among the companies that did co-operate with the ACCC was Jetset Traveland.
The travel agency recently agreed to ACCC demands it remove no liability clauses requiring customers to waive chargeback rights through credit and debit cards.
Chargeback involves asking your bank to reverse a transaction in cases of a product not being provided and are generally available.
Melbourne gym GFC Berwick also paid $6,000 to the ACCC last year as a penalty for falsely claiming to members that the carbon tax would force a fee increase.
National unfair contract terms came into effect as part of Australian Consumer Law in 2010.