The governors of a Jesuit-run school must face a £5m action from an ex-pupil who claimed he was sexually abused.
Preston Catholic College has lost an appeal against a court ruling which gave Patrick Raggett, 52, of west London, the right to claim damages.
Mr Raggett alleged he was assaulted regularly over a four-year period.
The college's governors said the claim came outside the legal time limit and denied liability, but their argument was dismissed by the Court of Appeal.
Mr Raggett said he was "very pleased" with the decision, which was taken by Lords Justices Mummery, Thomas and Toulson.
"I remain resolute and confident that, in the end, justice will be achieved," he added outside the court in London.
But he said the ruling was "only another stage on what is a long road".
Mr Raggett claimed the late Father Michael Spencer sexually assaulted him at the Lancashire school, sometimes several times a week.
The priest - who died in 2000 - allegedly measured the schoolboy "to chart his growth" while he was naked, filmed and photographed him and touched him inappropriately.
Lord Justice Thomas said the evidence against Father Spencer was "strong", particularly because of evidence given by Mr Raggett's contemporaries at the college, which closed in 1978.
And Mrs Justice Swift dismissed the governors' claim that too much time had elapsed for a case to be brought, stating she was satisfied that it was possible for the action to go ahead.
The £5m which Mr Ragget is seeking includes the past and future loss of earnings as a City lawyer
He claimed he had suffered years of under-achievement at work, along with a failed marriage, binge-drinking and a breakdown.
In a statement, the British Jesuits said they had "fully noted" the judgment and were considering its implications.
They said they "recognise the claimant's right to proceed with his claim for damages" and "deeply regret any abuse he suffered during his time at Preston Catholic College".