Convicted Washington-area sniper John Allen Muhammad should never have been allowed to act as his own lawyer for part of his 2003 capital murder trial, his attorney said yesterday in a federal appeals hearing.

Muhammad's conviction and death sentence should be thrown out because his trial lawyers failed to tell a judge that the mastermind of the 2002 shootings was too mentally impaired to represent himself, attorney Jonathan Sheldon said.

A lawyer for the state of Virginia argued Muhammad's competency was never an issue in his trial for one of 10 killings committed by Muhammad and teenage accomplice Lee Boyd Malvo. Muhammad was sentenced to death, and Malvo is serving a life term for the shooting spree.

Muhammad represented himself for the first two days of his Virginia trial, making his own opening statement and questioning 18 witnesses before turning his defence over to court-appointed attorneys.

Sheldon, who is handling Muhammad's federal appeal, said the trial lawyers violated Muhammad's constitutional right to effective counsel by not telling the judge about their client's delusional statements and brain disorders stemming from childhood beatings.