The brother of Norway's controversial crown princess has been jailed for 60 days for assault.
Mette-Marit and Haakon are expecting a baby in January
Espen Hoiby, a 44-year-old airline pilot, was found guilty of attacking and beating his former girlfriend at a party two years ago.
Hoiby denies deliberately hurting the woman and plans to appeal against the verdict.
Correspondents say the news is one more in a series of blows to the image of the royal family, which has traditionally been renowned for its modesty and discretion.
Crown Princess Mette-Marit, who married heir to the throne Prince Haakon in August 2001, has herself drawn criticism for her past as a party animal and single mother.
But she appears to have won the hearts of the public, and is expecting a baby in January.
Prince Haakon's older sister Martha Louise also came under fire for her marriage last year to writer Ari Behn.
At the trial, Hoiby admitted to shoving his former girlfriend.
But she said that he had knocked her over and kicked her as she lay on the ground.
As well as receiving a jail sentence, Hoiby was fined 40,000 kroner (4,852 euros).
He has been suspended from piloting duties.