It is understood Edinburgh City Council could consider another court tangle involving its own arm's-length company.
It was set up to deliver major transport projects in the city and a firm that provided it with advice.
The news comes as an online campaign and petition was launched for a public inquiry into how the project cost £776 million, more than the original £545m, and arrived three years late.
The trams begin running for passengers tomorrow at 5:29am from York Place and about every ten minutes after that up to 11.10pm along eight miles and 15 stops to and from the airport.
The project has been mired in controversy after it stalled for two years following a dispute between Transport Initiatives Edinburgh (TIE), the company the city council set up for transport projects, and contractors.
It is understood a recent legal move at the Court of Session would help to protect the council's future right to raise a court action if it opted to do so.
A hearing involved Edinburgh City Council, TIE and DLA Piper Scotland, a firm which provided legal advice to TIE.
The council said in a statement: "Cases were called in court on Friday May 16 as a protective measure to interrupt the legal prescriptive period and prevent any rights of action being lost."
A DLA Piper Scotland spokesman said: "The firm has always strongly refuted any wrongdoing with regard to work undertaken in relation to the Edinburgh tram project for Tie Ltd, on behalf of Edinburgh City Council.
"We now welcome the opportunity to set out the firm's position in respect of the allegations which will be vigorously defended."
A spokesman for the Scottish Government said: "As we have said on many occasions before we would welcome a public inquiry.
"The current focus is rightly on ensuring that the people of Edinburgh receive an effective passenger service once it is up and running on May 31.
"We would then intend to meet with the council to discuss how any inquiry could be best structured to establish clear lessons for similar projects going forward.
"We are also aware of the council's decision to continue outstanding legal proceedings against other key advisers to the project (not Transport Scotland) and both await the outcome with interest and note the proceedings could potentially impact on the timing and thereby scope of any inquiry."
Campaigners feared new legal action could delay a public inquiry for years.
Daniel Donaldson is the Edinburgh lawyer who set up the petition which in a few hours had attracted 50 signatures.
He said: "Lessons have to be learned concerning how large scale, public infrastructure projects of this type are procured, managed and audited for public value.
"If lessons are not learned from the Edinburgh Trams project, there is a real risk that we will all pay the price again in the future.
"The circumstances are now right, there can be no further excuse for delay. It's now time for the public inquiry."
Andrew Kettler, of Edinburgh, said he supported the push online.He said: "The waste of public money must be investigated, the tram line has resulted in long term damage to both the fabric, commerce, and financial health of the city, and to the environment."
Cameron Rose, Edinburgh Tory group leader, also said the inquiry should be held now adding "even favourable predictions tell us it will not break even in revenue terms for years".
The council said the trams were expected to bring environmental and economic benefits to the city, including jobs and investment.