L. Clifford Davis, a civil rights lawyer who led efforts to desegregate high schools in Texas, sometimes in the face of mob violence, hostility from state politicians and threats on his life, died on Feb. 15 in Fort Worth. He was 100.

His daughter Karen Davis confirmed the death, in a nursing facility.

Although the U.S. Supreme Court outlawed public school segregation in 1954 in its ruling in Brown v. Board of Education of Topeka — a case on which Mr. Davis had worked alongside Thurgood Marshall in its early stages — many cities and states across the South initially defied the ruling.

It was left to lawyers like Mr. Davis to hold those local districts to account. He began with Mansfield, Texas. The town’s only high school was whites only, and Black students had to find their own way to a Black high school, traveling 20 miles to Fort Worth.

On behalf of five students, Mr. Davis sued the Mansfield school district in 1955, and a year later a federal appeals court ruled in their favor.

But when Black students arrived for the first day of school in September 1956, they were met by hundreds of angry white people, some holding nooses. Burning crosses were on display.

Mr. Davis appealed to the U.S. attorney general, Herbert Brownell Jr., for help, but he refused. Mr. Davis then wrote to Gov. Allan Shivers of Texas.

“These Negro students are exercising a constitutional right,” Mr. Davis wrote. “I call upon you as Governor to cause to be dispatched additional law enforcement officers to Mansfield to assure that law and order will be maintained.”

Governor Shivers deployed the Texas Rangers — but only to keep the peace. He made it clear that he would do nothing to enforce the integration ruling.

At one point, a friend of Mr. Davis’s offered him a handgun for protection, warning him about white vigilantes. He took the weapon but never used it. He did, however, receive death threats in the mail, though he shrugged them off.

As tensions rose, Mr. Davis decided that the risk to the students was too great, and he pulled back his efforts to bus them to white schools.

But he continued to press the cause. In 1959, he brought a class-action suit against the Fort Worth school system, which remained segregated. He won, and this time the system agreed to a plan to integrate its schools.

Such work, he later reflected, was the epitome of what lawyers should aspire to do.

“The philosophy that was instilled in us in those days was that lawyers were social engineers,” he said in a 2014 oral history interview for the University of North Texas. “It was our job to try to use the principles of law to help bring about equality and opportunity for all people, not just Black people.”

L. Clifford Davis (the initial L. did not stand for a name) was born on Oct. 12, 1924, in Wilton, in southwestern Arkansas, where his parents, Augustus and Dora (Duckett) Davis, were sharecroppers.

Wilton was deeply segregated, and the local Black school system stopped at the eighth grade. Clifford’s parents rented a house in Little Rock, the state capital, where he and five of his six siblings lived while attending high school and college.

He graduated from Philander Smith College (now Philander Smith University), a historically Black institution, in 1945 with a degree in business administration.

Mr. Davis wanted to go to law school, but there were none in Arkansas that would accept Black applicants, so he moved to Washington, D.C., to attend Howard University.

Finding the cost of living in Washington too high, however, and feeling that the time was ripe to attempt to desegregate the law school at the University of Arkansas, he applied for admission there in 1947.

The school, in Fayetteville, offered him a spot, but with a big caveat: He would have no contact with white students and would have to pay his tuition in advance.

Mr. Davis declined and remained at Howard, graduating in 1949. But his efforts did not go to waste. In 1948, Silas Hunt, taking the same offer, became the first Black student at Arkansas’s law school.

Mr. Davis initially practiced law in Pine Bluff, south of Little Rock. He moved to Texas in 1952, settling in Fort Worth, where he became the city’s first Black lawyer to open a practice.

He worked with the N.A.A.C.P. and other civil rights groups, participating in the early phases of the case that became Brown v. Board of Education, led by Thurgood Marshall, the future associate justice of the Supreme Court.

In 1983, Mr. Davis was named a criminal district court judge, and the next year won election to the post. He lost re-election in 1988 but remained a visiting judge until retiring in 2004.

Along with his daughter Karen, he is survived by another daughter, Avis Davis. His wife, Ethel (Weaver) Davis, died in 2015.

Judge Davis was not one to seek the spotlight, but in time it found him. In 2012, the Fort Worth Black Bar Association, which he helped found in 1977, renamed itself the L. Clifford Davis Legal Association in his honor.

And in 2017, the law school at the University of Arkansas awarded him an honorary degree.

“It never crossed my mind that this would happen,” he told The Arkansas Democrat-Gazette. “I applied 71 years ago to earn a degree. Now they’re going to give me one.”