P&O Ferries will not face prosecution for its mass sacking of 786 workers.
The Insolvency Service, which carried out a a criminal investigation into the redundancies in March, said prosecutors had concluded there was no realistic prospect of a conviction.
The ferry company sparked nationwide protests when it sacked hundreds of staff with no warning though a recorded video message.
P&O, which claimed it had to act quickly because it was losing £1m a day, brought in cheaper agency workers to replace the employees.
Legal experts said they believed P&O had acted illegally in not consulting over the redundancies and the company’s boss admitted it had breached employment law.
Outrage was compounded this week when the company’s owner, DP World, announced profits of £736m in the six months to the end of June.
And transport secretary Grant Shapps tried to force the company to reinstate the workers with a package of measures including asking ports to refuse to deal with P&O.
He also called for company boss Peter Hebblethwaite to quit.
During hearings in Parliament, he admitted his company had broken the law that required them to give staff notice.
Business secretary Kwasi Kwarteng asked the Insolvency Service to investigate whether any offences had been committed.
An Insolvency Service spokesperson said on Friday evening: “After a full and robust criminal investigation into the circumstances surrounding the employees who were made redundant by P&O Ferries, we have concluded that we will not commence criminal proceedings.”
An independent senior prosecution lawyer reviewed the investigation and decided there was no realistic prospect of a conviction, the spokesperson added.
However, a civil investigation by the Insolvency Service is continuing.