Dr Bryn Harris, the chief legal counsel at the Free Speech Society, was reacting to the conclusion of a libel case involving the two politicians this week.
Mr Carson – who is no longer a councillor or a DUP member – had written back in April 2021 that he expected the new leader of the DUP would put Ms O’Neill “in her kennel”.
Ms O’Neill then resorted to the courts, claiming he had defamed her.
Mr Carson said sorry, but the legal action against him continued regardless.
Then in the High Court in Belfast this week, the judge said given Mr Carson’s relatively lowly position as a councillor, his comments had basically no impact on her reputation.
As a result she was not entitled to and damages, and both she and Mr Carson were left footing their own legal bills of about £13,000.
The judge also voiced displeasure at how much court time the case had taken up, and indicated that the case should never have got as far as it did.
“This is certainly a disappointing case,” said Dr Harris.
"Carson's comments may well have been injudicious, but the law usually expects politicians to tolerate a greater degree of criticism than other citizens in order to preserve the freedom to comment on the political process, even in robust or offensive terms.
"In turn, Carson himself should also have been afforded a high level of free speech protection as an elected politician.
“It is therefore disappointing that the judge did not award Carson the costs of having to defend this arguably misconceived claim, particularly as it seems he made an apology.”
The judge, Master Bell, emphasised that Mr Carson has still paid a heavy price for the “stupid and offensive” posting, including the loss of his political career.
According to the information provided to the court, his legal costs exceed all the savings he has and, if his solicitor and counsel pursue him for those costs, he is likely to lose his house.
There has been virtually zero reaction to the court ruling, with the DUP itself being essentially silent about Mr Carson’s fate.