The case dates back to 2007, when Novartis hired a company in Poland to test a vaccine for bird flu following the Europe-wide outbreak of the H5N1 virus.
The trials were carried out on homeless and poor people in the Polish city of Grudziadz, where they were paid around two francs for participation.
But one former subject, named as Grzegorz S, says participants were told the vaccine was for the conventional flu virus, and he has launched a civil suit against the Basel-based company.
According to consumer magazine Beobachter, the man had no idea that the vaccination was administered as part of a clinical trial.
"I never agreed to be used as a guinea pig. If I had known what the vaccinations were, I would not have participated," he told the magazine.
The man's lawyer told Swiss broadcaster SRF that no agreement had been reached in arbitration at the start of July, and that his client was now suing the pharmaceutical giant for 100,000 francs.
Although Novartis did not carry out the trials directly, the lawyer said that "the sponsor of the tests; whoever arranges them and takes the profits, must be responsible for the actions of their auxiliary staff".
After the tests, the director of one Grudziadz homeless centre, Mieczyslaw Waclawski, told a Polish newspaper that 21 people from the centre had died. While the deaths were not conclusively linked to participation in the trial, the figure was a significant rise from the average of around eight.
A criminal case into the trials was concluded in Poland earlier in 2017, with three doctors and six nurses charged, though Novartis was not put under investigation in connection with that case.
In a statement, the Swiss company said it was committed to "meeting the highest standards at all times" and following the research ethics set out in the Declaration of Helsinki.