WASHINGTON (AP) _ The Supreme Court today agreed to consider broadening protection for criminal defendants who claim they were denied adequate help by lawyers in filing appeals.

The court said it will review a ruling that threw out an appeal by an Ohio man convicted of rape, robbery and assault.

The defendant, Steven Anthony Penson, was convicted of charges stemming from a breaking and entry by three men into a Montgomery County, Ohio, home on Aug. 4, 1984.

The three intruders sexually assaulted a man and two women, and also robbed the home.

After Penson was convicted and sentenced to 18 to 28 years in prison, his attorney refused to file an appeal on grounds there was ''no meritorious issue'' for an appeals court to consider. Lawyers for Penson's two convicted co-defendants did appeal their convictions.

Penson's lawyer then withdrew from representing him and Penson filed his own appeal.

An Ohio appeals court said it was troubled by the conduct of Penson's lawyer. But the appeals court said, ''We find (Penson) has suffered no prejudice in his counsel's failure to give a more conscientious examination of the record.''

The appeals court upheld Penson's conviction.

The Ohio public defender's office that was later assigned to the case said in its appeal to the Supreme Court that Penson's rights were violated.

The public defender said the burden of proving Penson received ineffective legal assistance in pursuing his appeal improperly was placed on the defendant. The public defender argued that Penson should not be required to show specific omissions or errors to establish a presumption he received inadequate representation.

Penson's original lawyer, in refusing to file the appeal, failed the requirement that he state in writing the grounds that arguably could support an appeal, the public defender said.

The public defender urged the Supreme Court to elaborate on a 1967 ruling that set some standards to judge the effectiveness of lawyers handling appeals.

The case is Penson vs. Ohio, 87-6116.