May 3 (Reuters) - Clarence Thomas this week will reach a major milestone on the U.S. Supreme Court, becoming the second-longest-serving justice in American history. Along the way, the stalwart conservative has played an important role in guiding the court on a rightward course, even if he has not gotten everything he has advocated.

Thomas, who is 77, has served since October 1991, having been appointed at age 43 by Republican President George H.W. Bush to replace liberal luminary and civil-rights pioneer Thurgood Marshall on the top U.S. judicial ‌body. Marshall was the first Black member of the court. Thomas, after a contentious Senate confirmation battle, became the second.

Thomas on Monday will overtake Justice Stephen J. Field, who served from 1863 to 1897, for the court's third-longest tenure, according to the Supreme Court Historical Society. Thomas ‌on Thursday will leapfrog his late former colleague Justice John Paul Stevens, who served from 1975 to 2010, for the second-longest tenure, the society said.

If Thomas remains until May 20, 2028, he would set the court's longevity record, passing Justice William O. Douglas, who served from 1939 to 1975, the society said.

Thomas has left his mark on the Supreme Court, even as his role has ​evolved over the years.

"He began his time on the court often in dissent, and he stood his ground," said Haley Proctor, a University of Notre Dame law professor who previously served as a clerk for Thomas.

"The justice's influence on the law has been profound," Proctor said. "And that is a consequence, not only of his many years on the court, but also of his persistence."

Thomas has helped the court's 6-3 conservative majority, in place since 2020, to act assertively. On back-to-back days in June 2022, he was the author of a landmark ruling expanding gun rights protected by the U.S. Constitution's Second Amendment and joined other conservative justices in overturning the 1973 Roe v. Wade decision that had legalized abortion nationwide.

Thomas also has championed an expansive view of religious liberty, opposed gay marriage, fought affirmative action preferences for minorities in university admissions and hiring, supported the death penalty and broad presidential powers, and curbed campaign-finance restrictions.

"Justice Thomas is the most radically conservative justice to serve on the Supreme Court in modern times," said Erwin ‌Chemerinsky, dean of the University of California, Berkeley School of Law. "I say this because in addition to being ⁠conservative he has taken positions that would dramatically change the law that the court never has accepted."

Source: Drudge Report