A Washington lawyer began his defense against sodomy charges yesterday by producing evidence apparently contradicting key statements made by the chief prosecution witness.

George T. Baker, a District of Columbia social worker called as the first defense witness, testified that Roger H. Moore, the lawyer charged with sodomy, was at the D.C. Superior Court building until about 2:30 p.m. on March 19 of last year, the day when one sodomy incident allegedly occurred.

Baker also told an Arlington County Circuit Court jury that the teen-age youth with whom Moore is accused of committing sodomy was logged into St. Elizabeths Hospital at 3:24 p.m. the same day.

If the jury accepts Baker's account, the alleged act of sodomy apparently could not have occurred at Moore's Arlington home because there would have been insufficient time. Baker also contradicted statements by the youth, who testified Wednesday that he arrived at St. Elizabeths at about 5 p.m. on March 19, 1979, after spending 30 minutes to one hour at Moore's home.

Under questioning by Moore's lawyer, Thomas J. Harrigan, Baker testified that the boy's reputation for truthfulness "would be very poor because he's known for many episodes of stealing, lying."

Yesterday was the second day of Moore's trial on charges of committing several acts of sodomy with the youth, who was 16 at the time. Another incident allegedly occurred on June 16, 1979. Moore's lawyer has not yet offered evidence to counter the June 16 allegations.

Judge Charles H. Duff recessed the trial until Monday morning.

Moore, 33, also has been indicted on additional charges of engaging in sexual misconduct with two other teenage youths whom he represented in legal proceedings. He is scheduled to be tried on these charges later.

Prosecutor William A. Nunn III called the two youths to the witness stand yesterday in an attempt to establish what he termed a pattern of sexual misdeeds by Moore. One youth testified about several alleged sodomy incidents at Moore's home last fall. The other told the jury that Moore patted him while the youth was clad in underwear at the youth's home in 1978.

Under cross-examination by Harrigan, one of the youths admitted that he burglarized Moore's home last November, previously confessed to robbing a 79-year-old man in the District of Columbia and had lied in key statements. a

Harrigan also said he could produce evidence that Moore was in California, rather than at his Arlington home, when one alleged incident occurred and that he was ill with a high fever at the time of another alleged incident.