Home Office officials wrongly charged 69 people with entering the UK illegally when they had not reached the country, it has emerged.
At least five men were jailed for a crime they did not commit as a result of the error, and will now have their convictions quashed.
The Independent understands that they are likely to be held in immigration detention, as they can still be classed as “illegal entrants” without a conviction.
The Home Office said it would deport “anyone found to have no right to remain in the UK”.
The vessel, sailing from Ostend in Belgium, was the target of a joint operation involving the Home Office’s Immigration Enforcement unit, Border Force and the National Crime Agency.
All 72 people on board were arrested after two Border Force ships escorted the boat to Harwich harbour.
The interception at sea and immediate detention means they had not entered the UK or committed a crime under the Immigration Act, but Immigration Enforcement prosecuted 69 passengers using the law.
On Wednesday, the Crown Prosecution Service (CPS) announced that it was stopping proceedings against the passengers because the case failed on evidential grounds.
At least five men had already pleaded guilty to entering the UK illegally and were jailed. Their convictions will be returned to court to be quashed.
The three crew members, a Latvian national and two Ukrainians, have been charged with facilitating illegal immigration.
A spokesperson for the CPS said: “Following the interception of a fishing vessel off the East Anglian coast last month, we have authorised charges against three people for facilitating illegal entry to the UK.
“After careful consideration, we have decided our legal tests for prosecution were not met in relation to the 69 passengers. Proceedings commenced by Immigration Enforcement will therefore be discontinued and any convictions returned to court.”
The offence of illegal entry is not known to have been used in such circumstances before and can only apply to people who reach land.
The Immigration Act states that people are not deemed to have entered the UK “unless and until he disembarks” and leaves a port.
It adds: “A person who has not otherwise entered the United Kingdom shall be deemed not to do so as long as he is detained.”
All 72 people on board the fishing vessel were arrested and detained immediately in Harwich, in an operation supported by Essex Police.
At a hearing at Suffolk Magistrates’ Court two days later, five passengers who pleaded guilty to unlawful entry were jailed for two weeks.
The Eastern Daily Press reported that defence solicitor David Allan said they came to Britain due to “economic and financial circumstances resulting in fairly extreme hardship”.
The court heard that two other passengers may be passed to the national referral mechanism for identifying victims of modern slavery.
The proceedings were dropped amid mounting concerns over the legality of changing Home Office policy on English Channel crossings.
Eight migrants have been jailed so far this year for piloting dinghies, after Immigration Enforcement started using drones to identify them and arrest them on arrival in the UK.
They are then referred to the CPS to be charged with “assisting unlawful immigration”.
The offence, which was previously used against people smugglers working for profit, has a maximum penalty of 14 years’ imprisonment.
The home secretary has repeatedly branded migrants who steer dinghies “people smugglers” but a judge ruled that they were “not acting as part of a trafficking gang“ in October.
Letters sent to the home secretary and director of public prosecutions by a legal group said there were “considerable doubts as to the legality of this new policy” and called for charges to be suspended.
The Home Office insisted that courts have upheld its approach in several cases that ended with significant prison sentences.
But in further legal trouble for the department, a High Court judge ordered officials to change the way they interview arriving migrants following concerns signs of trafficking were being missed.
Mr Justice Fordham found that asylum screening interviews had been curtailed since the start of the coronavirus pandemic, victims who should have protection from prosecution and deportation could have been missed.
There are also continued legal battles over deportation flights, where the Home Office has been condemned for attacking “activist lawyers” for stopping removals.
A Home Office spokespersoncalled the operation “successful” and hailed the three charges for facilitating unlawful immigration.
“We are disappointed that the proceedings against the 69 people charged with illegal entry will be discontinued and we are working with the CPS urgently to resolve the issues raised by this case,“ a statement added.
”The immigration cases will be dealt with as quickly as possible and removal action will be pursued against anyone found to have no right to remain in the UK.
“Knowingly entering the UK without leave is a criminal offence and anyone who has committed such an offence should be prepared to face prosecution.”