During 15 days of testimony in D.C. Superior Court, prosecution witnesses have portrayed Dr. Robert J. Sherman as an assembly-line abortionist who used unsterile, broken and worn instruments.

Former patients testified that they were sent home after incomplete abortions and employes said Sherman routinely violated medical standards in order to cut costs and increase profits at his clinic in northwest Washington.

Today, Sherman's trial on charges of second-degree murder and 26 counts of perjury is expected to shift to the defense stage. His attorneys anticipate more than two weeks of testimony from medical experts, doctors and patients who they hope will counter the government's argument that Sherman - motivated by greed - disregarded the lives and safety of the women he treated.

The three-week-long trial has been slowed by often detailed medical testimony, the introduction of more than 80 pieces of physical evidence and numerous, often lengthy bench conferences. The proceedings took a dramatic turn midway in the government's case with sensitive testimony from young women who had gone to Sherman for abortions.

That testimony was climaxed with the appearance of Mrs. Lupe McDowell, who had accompanied her daughter, 16-year old Rita McDowell, to Sherman's clinic. Mrs. McDowell collapsed in tears as she described the circumstances that led to her daughter's death. Judge Fred B. Ugast immediately stopped the proceedings and the members of the jury, some of whom were visably moved by the incident, were led from the courtroom for a recess.

Another moment of drama came as one of Sherman's former patients was about to testify. A juror suddenly raised her hand and said "I know her!" The witness had dated a close relative of the juror's, became pregnant and had an abortion, the juror told Ugast. After some discussion, the juror was dismissed from the case and replaced by one of four alternate jurors.

When the trial opened Oct. 27, defense attorney Robert F. Muse asked the jury of seven women and five men "to be patient and to wait" while the government presented its case. When the defense begins, Muse said, the jury will learn about "Dr. Bob Sherman" whom he described as a "compassionate, decent doctor."

And they will hear evidence, Muse said, that Sherman used "good medical judgment" when he treated Rita McDowell about almost four years ago.

McDowell, then a 10th grade student at Spingarn High School and already the mother of a young son, went to Sherman's Columbia Family Planning Clinic for an abortion on March 4, 1975. Three days later, she was rushed from her home to D.C. General Hospital where she died 21 hours later.

The government, backed by testimony from the city's deputy chief medical examiner, contends McDowell's death was caused by severe blood poisoning and shock as a result of an incomplete abortion performed by Sherman.

Muse told the jury, however, that it was at the hospital that "the course" of Rita McDowell's death began.

Muse and co-counsel Constance O'Bryant contend that repeated attempts by doctors at D.C. General to insert a needle for an intravenous line below McDowell's collarbone caused puncture wounds, leading to an accumulation of fluid in her chest and death.

In his opening statement, Muse said doctors at D.C. General had "butchered" the procedure. Government witnesses have testified, however, that the doctors, principally an intern and a resident, acted properly when they made repeated attempts to insert the line, as part of a procedure needed to monitor McDowell's blood circulation pressure.

Muse and O'Bryant, both of the citys Public Defender Service, were appointed by a Superior Court judge to represent Sherman without charge after court officials determined he was indigent. In early September, days before his trial was to begin, Sherman told the court he was broke, that he had fired his private attorney and that he lived outside Richmond on a $63-a-week government pension.

Sherman, 65, reportedly paid close to $525,000 to settle a medical mal-practice lawsuit fild on behalf of Rita McDowell's son Tony after her death. Aaron M. Levine, an attorney who represented the McDowell family, said earlier that about 16 of an additional 21 lawsuits filed against Sherman in connection with his medical practice have been settled.

In Sherman's criminal case, the defense also is expected to present evidence to show that Rita McDowell was 12 weeks pregnant when she went to Sherman for an abortion, not 16 weeks as the government contends.

The government, represented by assistant U.S. Attorneys Carl S. Rauh and Whitney Adams, argues that Sherman deliberately performed abortions on women in his clinic past the 12th week of pregnancy, in violation of medical standards. Those standards recommend that abortions past the 12th week be conducted in a hospital because of the increased risk of complications, according to government witnesses.

The government opened its case with testimony from the medical director of Preterm, Washington's largest abortion clinic, who described what he said were proper abortion techniques and then narrated a 20-minute, color video tape of an actual abortion procedure.

One of the prosecution's final witnesses was the chief of gynecological services at Columbia Hospital for Women here, who answered a series of hypothetical questions based on testimony from other witnesses on practices at Sherman's clinic. Sherman's Columbia Family Planning Clinic was not affiliated with Columbia Hospital for Women.

Judge Ugast has reminded the jury repeatedly that Sherman is not charged with any crime related to the medical practices described by those witnesses. Ugast explained that the jury may consider that testimony in connection with the government's charge that Sherman acted with malicious disregard for his patient's safety. The government's evidence must show malice, an element of the second-degree murder charge.

The 26 perjury charges against Sherman relate to the government's contention that he conducted a coverup of the circumstances of McDowell's death. Three former employes testified they lied under oath at Sherman's direction about procedures at the clinic. The government charges Sherman lied 17 times under oath about those procedures.

The government has announced its intention to close its case against Sherman this morning. At that time, it is expected that Ugast will rule on a defense motion for a judgment of acquittal, based on the contention that the prosecution has failed to present evidence that could allow the jury to determine Sherman guilty beyond a reasonable doubt.

If the motion is denied, the defense would then begin presentation of its evidence.