When a Fairfax judge this week dismissed a $12 million libel case brought by Reston surgeon Dr. Harvey B. Jacobs following a 10-day trial, the maverick doctor rushed out and thanked the judge for being "one of the fairest I've had."

Jacobs' show of gratitude was not an idle compliment -- he's been in a lot of courtrooms.

In the last six years Jacobs, who served 10 months of a two-year sentence stemming from a federal mail-fraud conviction in May 1977, has been involved in a string of litigation perhaps unmatched by any individual in Northern Virginia.

Defense lawyers connected with Jacobs' most recent case say the physician has brought 28 lawsuits and in all but one of those suits he represented himself without a lawyer.

Jacobs, a trim, sandy-haired physician who favors casual tweed and corduroy jackets, has had a history of run-ins with lawyers and officials of Washington area medical societies.

His license to practice medicine was revoked in the District of Columbia, Maryland and Virginia as a result of his 1977 mail-fraud conviction. In 1974, according to court papers, Jacobs' temporary privileges at Prince William Hospital were withdrawn because he "made excessive charges to patients referred to him from the emergency room. . . "

Two years laters, the District suspended Jacobs from receiving reimbursement from the city's medicaid program "for questionable laboratory procedures and billings . . . " court papers state.

That same year Jacobs filed for bankruptcy, although local medical experts and attorneys claim Jacobs is not hurting financially. They note, for example, that the physician spares no expense during his trials and once flew to New York on a moment's notice to retrieve a document he was seeking.

Jacobs praised Judge Richard J. Jamborsky this week because, unlike many other judges Jacobs has gone before, Jamborsky did not interfere with Jacobs' presentation to question him about points of legal procedure. At one point, Jamborsky gave Jacobs' case a big boost when he overruled several defense motions aimed at excusing the Medical Society of Virginia as a defendant in the libel case. Had Jacobs won his suit, that ruling would have enhanced his chances of collecting greater money damages.

Commenting on the blizzard of lawsuits Jacobs has filed, Alexandria lawyer Philip Hirschkop, who was sued three times by Jacobs after representing him during his mail fraud trial, said: "Clearly, he's tying up the courts." Hirschkop says two of Jacobs' lawsuits against him were dismissed and Jacobs paid him $12,000 in settlement of the third. "I personally think his suits are frivolous," Hirschkop said.

"I'm not litigious," retorted Jacobs. "But when some of these people start sticking it to you, what do you do? I file a suit. And every suit I've filed has always been meritorious."

While few judges or lawyers will openly criticize Jacobs, privately they decry the often elaborate, sometimes frivolous-seeming and time-consuming complaints that Jacobs has brought in local, state and federal courts.

A typical case cited by many of Jacobs' critics is the $3 million antitrust suit he brought against the American Medical Association and medical malpractice insurers last year.

Jacobs subpoenaed 100 witnesses and tried to enter 3,000 documents as evidence to support his claim that he was expelled from several medical societies and lost privileges at local hospitals as reprisals for advertising his legal services and for indicating a willingness to testify against other doctors in malpractice cases. The suit was dismissed in July 1980 for lack of evidence. Jacobs has appealed.

Jacobs' most recent court case was the $12 million libel suit against the Fairfax Medical Society and its director, John Fitzgerald, that he lost last week. Jacobs, who was expelled from the county medical society in 1976, claimed that Fitzgerald wrote in a letter that Jacobs had "morals. . . as loose as tourists' bowels after three days in Mexico."

Fairfax Circuit Court Judge Jamborsky dismissed the case after siding with defense attorneys who claimed Virginia's one-year statute of limitation on libel claims had passed.

"I don't think we won, we survived," said William O. Snead, who represented the Fairfax Medical Society in the suit. "He Jacobs clearly enjoys the litigation."

Jacobs said he currently makes his living heading two firms, Malpractice Research Inc. and the Medical Quality Foundation, which furnish physicians to do research in medical malpractice cases. He refused to characterize his lawsuits, saying their only common point is that they "concern me."

Maryland relicensed Jacobs this summer on a probationary basis, and he testified in court that he has seen some patients since then.

"I'm a doctor with a conscience," said Jacobs, who once took out ads in local papers soliciting patients with the provocative query: "Are you tired of paying for your doctor's Cadillac and country club?"

In Fairfax, he said, "they have 10 to 20 doctors that want to run the whole show. The patients here need help. There is a conspiracy of silence."