A female teacher at a youth justice residence has been deregistered after marrying a male student who was half her age.
The teacher was 32 and the student was 16 when they first met in 2010.
The student was jailed for two years from September 2011 and later married the teacher in January 2016. By that time he would have been about 22 and she would have been about 38.
The Teachers Disciplinary Tribunal has found that the relationship was inappropriate even though both were adults by the time they married.
"This case shows that even when a teacher is no longer teaching a student, an intimate relationship may not be appropriate," it said.
"Teachers retain a professional responsibility to their students, particularly those who are deemed vulnerable because of their age."
All names and identifying details have been suppressed to protect the former student.
The teacher told the tribunal's complaints assessment committee in May 2015, before they married, that there had been "no sexual relationship".
"She repeated those denials in a meeting with the [committee] in December 2015 and said she had not really had any contact with the student during the past four years," the tribunal said.
"However she was living with him at the time and married him the following month."
The tribunal did not accept her claim that the relationship only started in July 2015.
"We, however, found Teacher C to be neither a truthful nor reliable witness and reject her evidence that this is when the relationship began," it said.
Instead, it found that the couple began an intimate relationship in early 2013 when the former student was in jail.
"The student was vulnerable, and at the time the intimate relationship commenced Student A would have been in his last year of school or just finished it, had he not been in prison," the tribunal said.
It found that the age difference between them was relevant as it "tends to accentuate the power imbalance".
The tribunal found that the teacher was guilty of "serious misconduct". She was censured and her teaching registration was cancelled.