Dexter Anton Forbes, the resident "jailhouse lawyer" at Lorton Reformatory, has lost his bid to have his conviction for armed assault overturned by the D.C. Court of Appeals.

When informed of the court's 2-to-1 decision against him, Forbes, who is serving a sentence of 15 to 45 years for the offense said "I'm not too surprised. That court's a pretty conservative court."

At Forbes' trial in the D.C. Superior Court before Judge John R. Hess, the government had contended that Forbes fired a sawed off shotgun into a man's face after demanding drugs and money. Forbes had consistently maintained that he is innocent of the charge.

Appeals Court Judge George R. Gallagher writing for the majority, rejected Forbes' arguments that he had been denied a speedy trial, that the jury had been improperly instructed on Forbes' alibi defense and that Hess wrongly denied Forbes a new trial based on Forbes statement that there was newly discovered evidence.

Forbes' case was argued in the Court of Appeals by lawyers for the city's Public Defender Service.

Gallagher and Associate Judge John W. Kern III rejected Forbes' argument that his conviction should be reversed because the trial judge did not caution the jury about contradictory statements made by a key defense witness. Judge Julia Cooper Mack dissented, saying the failure to give the instruction could have confused the jury and denied Forbes a fair trial.

Forbes now works five days a week as a library technician at Lorton and is paid $8,900 a year under the Comprehensive Employment Training Act.