On 13 September 2017, five Jamaican fisherman set out in the Jossette, a two-engine boat made of fiberglass and wood.

Their destination was an island group named Morant Cays – a popular haunt for fishermen about seven hours from home.

Patrick Ferguson, who owned the Jossette, planned on retrieving catches from fish traps that were set several days before the men departed. The rest of the crew – Robert Weir, Luther Patterson, David Williams and George Thompson – were going to help with these traps, while also angling for tuna and snapper.

They traveled simply, packing their fishing gear, overnight bags and a change of clothes. Ferguson’s fighting rooster, Jah Roos, also came along.

They only expected to be gone one day.

Instead, they wound up chained to the decks of four US Coast Guard ships for more than a month, a new lawsuit filed by the American Civil Liberties Union alleges. They were stripped naked, had their boat burned and were then taken to Florida where they were charged with drugs offenses – which were later dropped.

The men were gone for a year. At first, their families assumed they had died at sea.

The ACLU says the men were ensnared under the Coast Guard’s “unlawful detention and mistreatment policy” that “ramped up in 2012 as part of the United States’ ‘war on drugs.’”

It said: “Under this policy, the Coast Guard stops boats in international waters, searches them and their crew for drugs, destroys boats, and detains crew members for prolonged periods of time in inhumane conditions, regardless of whether any drugs are found aboard.”

It began when the boat got lost. Shortly after daybreak a day after they left Jamaica, the wayward crew headed toward a distant land mass in the hope of finding their way – not realizing it was Haiti.

A coastguard ship named Confidence spotted the Jossette. Officials said the men were spotted throwing packages of marijuana off their boat – something the men deny.

The lawsuit, filed on Wednesday, says: “The officers wrongly suspected the boat and its crew were involved in trafficking drugs, and dispatched four armed Coast Guard officers in a high-powered speedboat to stop, board, and search the Jossette and its crew.”

The Jossette was intercepted at about noon as three Coast Guard officers on the speedboat had their guns pointed at the fisherman, the ACLU suit states.

The fishermen told officers they were from Jamaica and had got lost. They provided ID and registration documents. The men and Jossette were searched, and no drugs were found, the ACLU alleges.

But a Coast Guard officer said they were to be taken on to the Confidence and detained.

Plaintiffs Patrick Ferguson, Luther Patterson and Robert Weir. Photograph: ACLU

“Shocked by this turn of events, the men initially refused to leave their boat,” court papers say. “But when the officers pointed guns at them, they complied. Each of the men took his overnight bag and got into the speedboat.”

Two officers found Jah Roos, the rooster “and, after obtaining orders to do so from their Commanding Officer, killed the bird”.

“The officers forced them to strip naked,” providing them only with “white paper-thin coveralls and a pair of thin, disposable slippers”, according to the suit.

The Jossette’s crew was brought to the bow, “where the officers chained each of them by one of their ankles to metal cables that ran the breadth and length of the ship’s deck,” the lawsuit claims. Thirty men were already detained at the bow. “All were dressed in the same white coveralls, and chained by one of their ankles to the metal cables affixed to the deck.”

When night fell, the Jossette’s crew, still chained to the deck, “watched in disbelief as a Coast Guard officer fired a flare at the Jossette. The boat burst into flames and then sank after Coast Guard officers riddled its hull with bullets,” the lawsuit alleges.

They remain ankle-chained to Confidence’s bow for four days, and were freed from the cable only “to relieve themselves in buckets or over the side of the ship.” Their only protection from the elements was a plastic tarpaulin hung over them.

The Confidence stopped at Guantánamo Bay, and the men were brought on to the second of four ships where, for one month, they allegedly endured inhumane conditions.

They finally arrived in Miami a month later, where each of the men pleaded not guilty to one count of conspiracy to possess with intent to distribute marijuana.

Those drugs charges did not stick. But the men pleaded guilty to “knowingly and intentionally provid[ing] materially false information to a federal law enforcement officer during a boarding of a vessel regarding the vessel’s destination”, court papers state.

The ACLU suit says: “They pleaded guilty because they were told that it was the quickest and surest way to get back to their homes and families in Jamaica and to put an end to their nightmare.”

They were sentenced to 10 months in US prison, and deported in autumn 2018.

In a statement the US Coast Guard said the men had been detained because its staff “observed the crew of the vessel jettison numerous packages of marijuana”, some of which it recovered from the sea.

“All suspects are cared for humanely while preserving the security of both the crew and suspects.”