A DECADE and a half ago, I started my job as a public defender specializing in appeals and met my first client. He was a middle-aged prison inmate who had just appealed his conviction for an attempt to escape. I will call him ''John Allen.''
At Mr. Allen's trial, the prosecution and the defense had agreed on two facts. He had run from a secured hospital room and a guard had shot him three times in the back.
At the trial, Mr. Allen had offered a justification for his flight. His testimony was that the guard had taken him from the outpatient clinic to the hospital room so that the guard could conduct a passionate rendezvous with his girlfriend, a hospital worker. When Mr. Allen asked them to stop, the guard turned and attacked the prisoner with a revolver. He then bolted.
The guard's version was that he took Mr. Allen to the hospital room to feed him. Mr. Allen had run from the room for no apparent reason. The hospital employee, to back the testimony, flatly denied being the guard's girlfriend.
The judge at the Allen trial had believed the testimony of the guard and the hospital employee and had convicted the defendant. The appellate court upheld my client's conviction.
Two years later, the guard was charged with a series of violent felonies that were committed outside the prison. At the guard's trial, his alibi witness was the hospital employee. She testified that she had been his girlfriend for several years. I realized that my first client had been convicted on the basis of perjured testimony and had deserved to be acquitted.
The public always has found it difficult to believe that the conviction of a few innocent men and women is inevitable in any system that is effective in convicting the guilty. In 1930, a New England prosecutor said, ''Innocent men are never convicted. Don't worry about it. It is a physical impossibility.''
A professor of law at Yale University, Edwin Borchard, heard of the prosecutor's boast. Mr. Borchard was aware of instances of erroneous convictions and decided to refute the widely held view that such cases did not exist. Encouraged by John H. Wigmore, the master of the law of evidence, and by then-Harvard law professor Felix Frankfurter, Mr. Borchard collected 65 documented accounts of men and women who had been convicted of crimes, imprisoned and later exonerated. He found four cases in which, after the defendant had been convicted and sentenced for murder, the '' murdered'' victim had turned up alive and well.
Mr. Borchard published his findings in his 1932 book, ''Convicting the Innocent: Errors of Criminal Justice.'' He concluded that the main causes of erroneous convictions were ''mistaken identification, circumstantial evidence (from which erroneous inferences are drawn), or perjury, or some combination of these factors.''
A quarter of a century after the publication of ''Convicting the Innocent,'' Federal Judge Jerome Frank described 36 additional cases of erroneous convictions in ''Not Guilty'' (1957). Judge Frank advocated a series of reforms aimed at avoiding the conviction of innocent defendants wherever possible. Over the years, several of the measures advocated by Judge Frank have been adopted in Maryland.
In 1972, Gov. Marvin Mandel and the General Assembly created the Office of the Public Defender to provide to all criminal defendants competent legal representation. In 1977, the Court of Appeals of Maryland issued a procedural rule that mandated broad pretrial discovery of evidence so that both the accused and the prosecution can prepare for trial.
In spite of the progress, an innocent man or woman may still become the victim of an erroneous conviction. In 1982, I was assigned to handle the appeal of a young man who had been convicted of participating in a break-in, rape, and robbery by four men at a suburban home.
At the time of his arrest, ''James Boyd'' worked part-time, served in the National Guard and had no criminal record. At Mr. Boyd's first trial, the principal victim had been unable to identify him, which had led to a mistrial. At Mr. Boyd's second trial, the victims improved their identification testimony and the jury convicted him. Before sentencing the defendant to life imprisonment, the veteran trial judge said that he believed Boyd to be innocent.
The Court of Special Appeals ruled that it could not overturn the jury's verdict, but said that ''We might have concluded differently.''
The late Judge Thomas Hunter Lowe wrote a separate concurring opinion ''to emphasize (his) discomfiture in affirming this judgment.'' Judge Lowe pointed out that the state had produced relatively weak identification evidence and that the defendant was similar in appearance to one of the other men who had been convicted of participating in the crime. He commented that the defendant's alibi evidence that he had been at another place at the time of the crime ''was as substantial as is possible . . .''