The legal action comes after the value of Brisbane's taxi licences plummeted by 79 per cent in recent years amid the rise of ride-sharing companies such as Uber and Ola.

Standard taxi licences in Brisbane were selling for an average of more than half a million dollars in 2014 but that price dropped to $103,828 in 2018.

Federal member for Kennedy Bob Katter has been supporting the legal action, which so far has more than 700 plaintiffs signed up, with plans for a meeting of taxi licence owners in Brisbane on Friday.

"The leadership of the state government will wish they have never heard the word 'Uber' by the time this case is over," Mr Katter said.

"The case is pretty simple - taxi owners had a property right, the right to operate a taxi.

"Government action destroyed the value of that property right and the Crown is liable."

Victorian barrister John Ribbands said there were about 3300 taxi licences in Queensland.

"Losses that each licence holder has faced basically exceed $300,000," he told ABC Radio Brisbane.

"So there's a billion dollars straight away before you even factor in things such as lost income and lost earnings."

Mr Ribbands said people bought taxi licences because the state government had created a scheme to ensure the viability of operators.

"What's happened is that with the legalisation of ride-share, that means that there is no value left in those licences," he said.

"They've been led into investing that money and now the rug's been pulled out from underneath them."

A statement of claim has been completed and was expected to be filed in the Queensland Supreme Court by early 2019.

Uber came to Brisbane in 2014, and ride-sharing was legalised in September 2016.

There were 58 standard cab licences sold in Brisbane in 2014 but caution swept the market in 2015, with only 11 transfers.

There were then 30 transfers in 2016 and 2017, and 28 so far in 2018.

Taxi Council of Queensland CEO Blair Davies said the fall in value had a "terrible impact" on owners.

"We've got people who were setting themselves up for their superannuation, they had a licence that was a piece of property that they could borrow against if they needed, or they could pass onto their loved ones as part of their estate," he said.

"Licence owners have had all of those plans destroyed by this change in the regulatory environment by the state government.

"Lots of people are holding onto the licences on the basis that they think it's worth more and of course the people who are buying the licences - they're just people shopping for a bargain."

The state government rolled out a $100 million assistance package for the taxi industry, including $20,000 per taxi licence, capped at two licences per holder.

But Mr Davies said that was inadequate when up to $400,000 had been wiped from the value of some licences.

Transport Minister Mark Bailey said ride-sharing services had been growing in popularity in Australia when the Palaszczuk government was elected in 2015.

"In August 2016, after consulting widely with the industry, RACQ, consumer groups and other major players, we announced reforms and an industry support package that was supported by the opposition and passed through Parliament unanimously," he said.

"Consistent with worldwide trends, we've seen an unprecedented level of disruption to the personalised transport industry, disruption that also delivered some significant improvements for customers in terms of choice and safety."

Taxi and limousine licence renewal fees will be waived for another 12 months.