As Norway’s higher education minister, Sandra Borch was responsible for making sure that students played by the rules. When one of those students was acquitted of the offense of plagiarism, Ms. Borch appealed, taking the case to the nation’s Supreme Court.

So it shocked the country when, just a few days later, Ms. Borch had to resign after it emerged that parts of her master’s thesis seemed identical to other reports that she had not referenced.

“When I wrote my master’s thesis around 10 years ago, I made a big mistake,” Ms. Borch said at a news conference on Friday, when she stepped down. “I took text from other assignments without stating the sources.”

The person who uncovered Ms. Borch’s misdeeds was Kristoffer Rytterager, a 27-year-old student in Oslo, who said he got “a bit pissed” that the minister went after an individual student for what he considered a minor mistake, and decided to look into the minister’s own academic work.

“When you are acting like you’re more sacred than a saint,” Mr. Rytterager said in an interview. “You shouldn’t have any skeletons in the closet.”

The case that angered him involved a student who had submitted an exam with some excerpts from a test she had turned in — and failed — the previous year. The student was suspended for two semesters in 2022, and her lawyer said the case had psychologically devastated her. More than a hundred professors and other academics signed a petition objecting to her treatment.