West Mercia Police has lost a legal bid to secure an order against a man who was said to have flaunted himself in his back garden only wearing a thong.
Malcolm Leonard Boorman, of Church Street, Kidderminster, was fined £100 in 2004 after he admitted harassing two female neighbours.
Police applied for an anti-social behaviour order (Asbo) based on alleged obscene behaviour at a window.
Magistrates declined the order and this was upheld in London's Court of Appeal.
Boorman was prosecuted over claims he paraded around his garden with his underwear "deliberately exposed".
He was also alleged to have performed a sex act at his bedroom window while rubbing baby oil onto his body and wearing only a thong.
'Long-range lens'
Magistrates found part of the prosecution evidence dated back more than six months and was not valid in court.
West Mercia Constabulary challenged this and Mr Justice Calvert-Smith accepted police arguments it could have been admitted. But he still rejected the police bid for a fresh hearing.
He said the behaviour was "at the bottom end of the scale in terms of anti-social behaviour".
Mr Justice Calvert-Smith said the case raised doubts about the admissibility of some prosecution evidence of video footage taken by the victims, who used a long-range lens to film Boorman inside his own home.
His lawyers argued that all that could be shown since the date of Boorman's guilty plea was a "gross invasion of his privacy" by the women complainants. They insisted there was no basis for imposing an Asbo.