The D.C. Court of Appeals overturned two armed robbery convictions yesterday against a District man with a long criminal record on the grounds that his right to a speedy trial had been violated under a special interstate agreement.

The ruling underscores the contradictions in some D.C. Superior Court practices and signals a need for change in the interstate agreement act or legislation providing for speedy trial provisions, court authorities said yesterday.

The unanimous three-judge panel threw out the armed robbery convictions of David V. Haigler under the Interstate Agreement on Detainers Act, which requires that defendants serving sentences elsewhere and then brought to the District be tried within 120 days of their arrival here.

The agreement, signed by 46 states and the District, has particular significance for the District because of its proximity to Maryland and Virginia. There is no speedy trial law in the District.

In the case before the panel, Haigler was serving a burglary sentence in Ohio when District officials ordered his return here to stand trial on six robbery charges. Haigler, identified by five cabdrivers as their assailant, was not tried in the first case for 384 days.

Court officials said if Haigler had been arrested in the District rather than discovered in an Ohio penitentiary the appellate panel most likely would have affirmed his convictions.

Although the appeals court has ruled that a one-year delay should trigger an inquiry into whether a case has taken too long, it regularly affirms convictions where far longer than 384 days has elapsed.

"I certainly think it's ironic that people who have the good fortune to be arrested outside the District have speedy trial rights," said Arthur Spitzer of the American Civil Liberties Union, "and that people arrested on the other side of Western Avenue for the same crime can be held in jail for a year or more without any effective right to a speedy trial."

Bills are pending in Congress and the D.C. Council that would force prosecutors to bring defendants to trial within 60 days of arraignment after indictment.

Haigler, 36, is serving a 15-year sentence in Ohio on burglary charges and has not yet been returned to the District to begin serving his two life sentences on the 1985 armed robbery convictions. After those convictions, prosecutors dropped the four remaining armed robbery charges.

Haigler had been accused of robbing six cabdrivers at gunpoint in March 1983, five of whom identified Haigler as their assailant at a police lineup. In addition to armed robbery and burglary charges, Haigler has been convicted of carrying a deadly weapon, receiving stolen property, grand larceny and attempted unauthorized use of a vehicle.

Because the appeals court ordered that the indictment be dismissed, Haigler, represented by lawyers G. Godwin Oyewole and Lawrence M. Baskir, cannot be tried again for the robberies unless the full appellate court vacates the panel's ruling. Judge Julia Cooper Mack, who wrote the opinion, was joined by Chief Judge William C. Pryor and Judge Theodore R. Newman Jr.

The U.S. attorney's office said no decision had been made whether to appeal.