Mr Justice Birss said Topshop's sale of a Rihanna T-shirt at the centre of the dispute was an act of " passing off".
But he said the "mere sale" of a T-shirt bearing the image of a famous person was not necessarily an act of "passing off".
He said a "substantial number" of buyers were likely to have been deceived into buying the Rihanna T-shirt because of a "false belief" that it had been authorised by the singer.
The judge said that was damaging to her "goodwill" and represented a loss of control over her reputation in the "fashion sphere".
He said it was for the singer not Topshop to choose what garments the public thought were endorsed by her.
More top news
Here is the letter sent by the broadcasters to Prime Minister David Cameron's office in relation to the planned TV leaders debates.
Machete-wielding armed robbers tied up staff and customers of a north Manchester pub during a terrifying raid.
The South African Salvation Army has used a picture of a dress that sent the web into meltdown to raise awareness about domestic violence.