Thomas Penfield Jackson, an outspoken federal judge who sent D.C. Mayor Marion S. Barry to prison for smoking crack cocaine and who declared Microsoft a monopoly that needed to be broken apart, died June 15 at his home in the Compton community of St. Mary’s County. He was 76.

He had cancer, his wife, Pat Jackson, said.

Judge Jackson, a native Washingtonian, ruled on many high-profile cases during his 22 years on the U.S. District Court for the District of Columbia and became known for his blunt assessments of the lawyers, jurors and defendants who came before him.

The Microsoft trial was called the most important antitrust case before a U.S. court since the Standard Oil breakup of 1911. The landmark case stretched 18 months, from 1998 to 2000, when Judge Jackson ultimately issued his ruling that Microsoft used monopolistic power to violate three antitrust provisions.

Beefy and six feet tall, Judge Jackson spoke in a deep, booming baritone and was a commanding courtroom presence. Observers noted that the judge quickly grasped the complex technical issues of the Microsoft case, but as the trial dragged on, his impatience became palpable.

Judge Thomas Penfield Jackson ruled that Microsoft was a monopoly that violated antitrust laws. (Associated Press)

Reporters noted that Judge Jackson rolled his eyes or scowled at statements by Microsoft’s attorneys and laughed during videotaped testimony by company co-founder Bill Gates. At other times during the proceedings, he appeared to yawn or nod off.

Judge Jackson issued his decision in April 2000, decreeing that Microsoft should be separated into two companies. Soon afterward, he stirred even greater controversy with a series of interviews in which he compared the computer software giant to a street gang and described Gates as “Napoleonic.”

It was rare — even unheard of — for a sitting judge to discuss his cases in such an unvarnished manner.

In reviewing Judge Jackson’s decision in 2001, a federal appeals court overturned his order that Microsoft should be broken up, but it sustained his primary ruling that the company acted as a monopoly.

But the appeals court wasn’t done. After addressing the legal issues, the judges issued a startling and sharply worded rebuke of Judge Jackson’s behavior in the case, charging him with “egregious” violations of judicial ethical standards.

The judges said he conveyed “the impression of a judge posturing for posterity, trying to please the reporters with colorful analogies and observations.”

Ultimately, they said, Judge Jackson ran the risk of undermining the authority of the courts: “Public confidence in the integrity and impartiality of the judiciary is seriously jeopardized when judges secretly share their thoughts about the merits of pending cases with the press.”

Earlier, Judge Jackson showed exasperation with the jury in the 1990 trial of Barry, who had been captured on camera smoking crack cocaine. After weeks of testimony and days of deliberations, the jury reached a decision on only two of the 14 charges against the mayor — and none of the felony counts.

Barry was convicted of one misdemeanor drug charge and acquitted of another. After dismissing the jury, Judge Jackson sentenced Barry to six months in prison and a $5,000 fine.

Less than a month after issuing his decision, Judge Jackson spoke to students at Harvard Law School. He said that there was “overwhelming” evidence against Barry but that some jurors “obviously did not tell the truth” when they said they could judge the case without bias.

Although Judge Jackson’s sentence was upheld, he was widely criticized for breaking the judicial code of silence.

Barry said he was a victim of what he called the “American injustice system.” His supporters noted that, just two years earlier, Judge Jackson had presided over the perjury trial of Michael K. Deaver, a onetime top aide to President Ronald Reagan. (Reagan appointed Judge Jackson to the federal judiciary in 1982.)

Deaver was convicted of a felony, but Judge Jackson sentenced him to three years of probation — without jail time — and a $100,000 fine.

Judge Jackson did not apologize for making a public example of Barry. The mayor had broken the public trust, he said, and needed to be held responsible for his actions.

In his sentencing decision, the judge wrote that Barry “has given aid, comfort and encouragement to the drug culture at large, and contributed to the anguish that illegal drugs have inflicted on this city in so many ways for so long.”

Thomas Penfield Jackson was born Jan. 10, 1937, in Washington and grew up in Kensington. His father, Thomas Searing Jackson, was a well-known lawyer.

Judge Jackson graduated in 1954 from Bethesda-Chevy Chase High School, where he played on the football team and was editor of the school newspaper.

He was a 1958 graduate of Dartmouth College, then served in the Navy on a destroyer. After graduating from Harvard Law School in 1964, he joined his father’s Washington law firm, Jackson & Campbell, which specialized in medical malpractice cases.

Judge Jackson was a lawyer for President Richard Nixon’s 1972 reelection committee.

Among his notable cases, Judge Jackson ruled that Oregon Sen. Robert W. Packwood (R) had to give up his personal diaries to a congressional panel during an ethics probe. Packwood later resigned.

in 1997, Judge Jackson struck down a law allowing presidents the power to veto line items in spending and tax bills, ruling that it violated the constitutional clause on separation of powers.

In one of his final rulings before his retirement in 2004, Judge Jackson ordered a North Carolina farmer, Dwight W. Watson, freed after 16 months in jail. Watson had driven his tractor onto the Mall to draw attention to the plight of farmers.

“Hallelujah!” Watson said after he was released. “Praise the Lord.”

Judge Jackson’s marriages to the former Jean Fitzgerald and Carolyn Gardiner ended in divorce.

Survivors include his wife of 21 years, Patricia King Jackson of Washington and St. Mary’s County; two daughters from his first marriage, Leila Kochis of Laguna Hills, Calif., and Austin, and Sarah Jackson-Han of Chevy Chase; a brother, Jeffrey Jackson of Bethany Beach, Del.; and three granddaughters.

After his public rebuke by the appeals court, Judge Jackson filed an official rebuttal in 2002.

“Our life tenure is all the more reason for us to be able to communicate informally on occasion with a public that must live with our decisions, yet can never vote us out of office,” he wrote. “One convention of federal judicial life to which I have never been fully reconciled is the notion the judges shouldn’t ever comment publicly about their cases — period.”