Washington - The US army has been ordered to reconsider the conviction of a doctor who treated John Wilkes Booth after he assassinated President Abraham Lincoln in 1865. Dr Samuel Mudd was jailed for helping Booth escape. Mudd's grandson, Dr Richard Mudd (97) of Saginaw, Michigan, sued last year to have his grandfather's conviction overturned. Federal Judge Paul Friedman in Washington DC sent the case back to the army, saying its recent rulings against the request were arbitrary. The morning after Booth shot Lincoln at Ford's The atre, he went to Mudd's home in Maryland seeking treatment for a broken leg. A military commission convicted Mudd in 1865 of aiding Booth in his escape. Troops killed Booth 11 days later. Mudd was pardoned by President Andrew Johnson, but his conviction was not overturned.