Thirteen months and six trial dates after Bernard A. Bowman was arrested and charged with armed robbery, he finally stood trial in the D.C. Superior Court and was convicted by a jury of robbery.

Yesterday, the D.C. Court of Appeals turned down Bowman's contention that the delays in his case denied him his constitutional right to a speedy trial. In so doing, the appeals court said that a lapse of more than a year between arrest and trial "may become the rule rather than the exception" in Superior Court.

In a long footnote, the court cited "an abundance of speedy trial contentions in recent ases" that have come before the appellate court.

". . . that upward trned undoubtedly will continue due to the overwhelming volume of criminal cases in the Superior Court," the court said.

Claims that the right to a speedy trial has been denied are often supported by arguments that the passage of time has somehow prejudiced the defendant and his case. For example, witnesses may become unavailable because of the delay, or their memory of events may have dimmed and thus damaged the defense's case.

The appeals court took note of the 1972 case in which the U.S. Supreme Court held that a defendant's rights were not violated, even though there was a delay of more than five years.

However, in the federal courts, new speedy trial legislation requires that defendants be brought to trial within 100 days of their indictment.

In its opinion, the appeals court noted that in Bowman's case, two postponements of trial were due to the trial court's congested calendar, one occurred when the prosecutor was unavailable and three were either requested by or agreed to by Bowman's lawyer.

After concluding that the delays did not prejudice either Bowman or his case, Judge Stanley S. Harris, in an opinion for the three-judge appellate panel, upheld the lower court's refusal to grant Bowman's request that the indictment against him be dismissed for want of a speedy trial.

In a footnote, however, the court noted that in a total of 1977, 3,417 persons were charged in Superior Court with felony violations, 12,872 persons were charged with serious misdemeanors and 5,296 deliquency petitions were filed against juvenile defendants.

"What that sort of caseload," the court said in the footnote, "the passage of more than 365 days from arrest to trial . . . may become the rule rather than the exception."