Scottish-born artist Peter Doig has won a long and strange trial over artwork authentication --- the living artist had to prove a painting was not his own.

A Chicago court ruled that Doig did not paint a landscape that former Canadian prison official Robert Fletcher said he bought from the artist while he served time in the 1970s. Doig maintained that he never painted the work or spent time in prison.

Fletcher sued the artist when Doig disavowed the artwork, once valued at $10m.

Signed "Peter Doige," the desert landscape was by another artist, argued Doig. Canadian Marilyn Doige Bovard testified to the court that the work was done by her late brother Peter Doige, and then the judge ruled for Doig.

Doig said: "That a living artist has to defend the authorship of his own work should never have come to pass."