Ned RocknRoll (34) says there is no public interest in The Sun publishing the photographs -- taken more than two years ago.
He says he is not a role model and had been a "relative nobody" prior to his marriage to Miss Winslet (37) late last year.
His lawyers told a UK High Court that publication would be a breach of privacy and could lead to Winslet's children being bullied.
But The Sun says Mr RocknRoll -- a nephew of tycoon Richard Branson -- has "propelled" himself into the position of "public figure".
Bosses say his conduct at the party in July 2010 might be regarded as "unacceptable".
And the newspaper's lawyers told Mr Justice Briggs that a "public interest" argument had arisen.
Mr Justice Briggs today heard legal argument from both sides at a hearing, which continues tomorrow, in London.
Part of the hearing was held in private. Little detail of what the photos showed emerged during the public section of the hearing.
The judge was told that photographs had been posted on a Facebook page belonging to Mr RocknRoll's friend, James Pope.
He heard that Mr RocknRoll had been wearing a costume and could be seen "partly naked".