A Prince George's County public defender was jailed and fined yesterday after he refused a judge's order to provide free counsel to a man with a $23,000 family income, a late model Cadillac and no children to support.

After emerging from the Hyattsville lockup, attorney Joseph M. Niland, said he and County District Court Judge Audrey Melbourne simply disagreed "withouth rancor" over whether a Kentland man with a job, a working wife and an expensive car should get free legal aid in a simple assault case.

"I just think I was right," Niland said, "I think (to provide free counsel for the man) would be a sham on the whole public defender system."

To the judge, "the orderly process of everyday court proceedings" was at stake, she later explained. There they were in the early afternoon she said: the prosecutor, the defendant, three civilian witnesses who had been waiting since 8:30 a.m. - and no defense lawyer.

"Joe Niland was in now way disrespectful," said Melbourne, who has been a judge for about a year.

Melbourne, Niland said, "has a good demeanor on the bench. She is very nice, very capable, very personable."

As Niland explained it, the situation developed when he interviewed the defendant early yesterday. The 26-year-old defendant had been interviewed once before by another member of the public defender's office and had qualified for free counsel. That other public defender, who could not be located yesterday, had entered his office's appearance in the court records and the trial was scheduled.

In yesterday's interview, Niland said he discovered the man earned $14,000 a year, his wife earned $9,000 and the two owned a 1970 Cadillac.

Maryland law is unclear on how poor a person has to be to qualify for free legal counsel. The statute speaks vaguely of "need" and "the financial ability of a person to engage competent private counsel" and pay othr defense costs. Obviously, Niland said, it costs more to defend against a murder charge than a simple assault and batter charge.

"Even if we have commenced representation, that's provisional, subject to change," he said. To represent a man who could afford to hire an attorney, Niland continued "would be a gross injustice to taxpayers and a complete disservice to the system."

These arguments failed to impress the judge, who denied what she said was Niland's motion to withdraw from the case. Cited for contempt, Niland was led by a deputy sheriff to a basement cell in the County Service Building where, he said, he spent the next hour or so.

Niland who is second in command of the county's public defender office, was then brought back to the courtroom for a further hearing on the matter. Still he refused to represent the man. Melbourne then found Niland guilty of contempt and assessed a fine of $10.

Niland didn't have $10 with him so Melbourne suspended the fine. She also continued the case. It is unclear who will ultimately represent the defendant. "After I disqualified him," Niland said, "he indicated to me he had a private attorney."