LONDON — The European Court of Human Rights ruled Tuesday that Britain could legally extradite five suspects wanted in the United States on terrorism charges, including Abu Hamza al-Masri, an inflammatory Egyptian-born cleric incarcerated in Britain but accused in a range of anti-American plots that date back 14 years.

In a major precedent that appeared likely to greatly ease extradition of Britain’s terrorism suspects, an issue that has surfaced repeatedly over the last decade, the court ruled that the human rights of the defendants would not be violated by their prospective captivity in a maximum security American prison. All face the possibility of life sentences without parole.

The decision was a defeat for human rights advocates, one that some legal experts called stunning, considering the court’s history of wariness toward the human rights standards of the American justice system.

When transfers of the five men might take place is uncertain. The European Court, based in Strasbourg, France, allows litigants three months to seek one last hearing from the court’s Grand Chamber. But legal experts said it was far from sure that the court would accept a further appeal, and Theresa May, the British home secretary, said the government would move “as soon as possible” on extraditing the men once the last legal steps had been completed.