Three seafarers are seeking compensation for being detained for two months in the US after exposing illegal oil dumping by German ship manager Mineralian Schiffahrt Sedition und Transport.
Third engineer Jarolsav Hornof of Czechoslavakia, oiler Damir Kordic of Croatia and wiper Lukas Zak of Slovakia saw "improper discharges" of oil from the 27,700-dwt Marguerita (built 2016), according to court documents.
Edward MacColl, the seafarers' lawyer, declined to comment on the case, other than to say: "My clients are wonderful people, friends of the earth and richly deserving."
The US government moved its case from under Marpol regulations to an obstruction of justice charge against MST, preventing the seafarers from collecting up to half the $3.2m fine.
US Department of Justice's Environmental Crimes Section declined to comment.
Calls to George Chalos, MST's attorney, were not immediately returned.
The court is expected to make a ruling next week.
Zak told Hornof, who boarded May 2017, that he noticed the illegal oil dumping several times since boarding the ship in September 2016.
Hornof said he saw the chief engineer set up pipes and hoses in such a way to allow oily bilge water to flow into international waters off Canada.
He said he told the engineer that the dumping violated Marpol's international pollution treaties and that he must stop.
When the engineer kept dumping the oil, Hornof videotaped the activity, took water samples and made statements for a US government investigation, documents filed with the US district court of Maine say.
Kordic and Zac also gave detailed information on the dumpings, which were not recorded in the ship's oil record book, when the ship arrived in Portland, Maine in July 2017.
The US government held the three seafarers for two and a half months in a hotel and took their passports to ensure they would be available as witnesses in its case to levy a $3.2m fine against MST.
In an affidavit, Hornof said his detention prevented him from helping his pregnant wife back home deal with her mother's passing while caring for their four-year-old son.
Kordic said he had a leg injury at the time and Zak said he was near the end of his 19-month contract in separate affidavits urging their timely release for home.
