A collection of companies based at the Port of Rotterdam are contesting a fine from the Dutch competition authority NMA at the European Court of Human Rights, arguing the sharing of intercepted phone calls violated their right to privacy.

One of the companies, Ships Waste Oil Collector, was fined by the NMA for anti-competitive behaviour in November 2011, after investigators looking into waste dumping heard employees discussing price fixing and handed the tapped phone calls over to the competition watchdog.

The company appealed the €834,000 fine, claiming the Dutch authorities violated the European Convention of Human Rights by sharing the call transcripts. “This could easily lead to abuse,” lawyer Margaretha van Heezik told the Strasbourg-based court.

The court joined the complaint from Ships Waste Oil Collector with similar complaints from five other maritime companies which were also fined earlier for acting as a cartel following other investigations.

The group is appealing against an earlier decision by a lower Dutch court which said there was no violation of privacy in handing over the transcriptions. The Dutch Supreme Court took the same decision in 2015.

“Should [the government] ignore such information?” Babette Koopman, who represented the Netherlands, said. She argued there were sufficient safeguards in place, including the approval of an official from the public prosecution department before the data was shared.