Justice Anthony Kennedy’s announcement that he will be retiring from the Supreme Court caps off a week of landmark victories for conservatives, from the public-sector union case to the travel ban. President Trump now has the opportunity to nominate a second justice to the high court.

In 2016, many voters took a chance on Trump in large part because of the list he put together of highly qualified individuals he would consider for a Supreme Court vacancy. But before the speculation begins about who his successor will be, it’s worth looking at Justice Kennedy’s legacy on the Supreme Court.

Appointed by President Ronald Reagan in 1987, Kennedy quickly became part of the “centrist” block on the court, along with fellow Reagan appointee Sandra Day O’Connor. With her departure from the court in 2005, Kennedy became the “swing” vote.

His judicial philosophy has not always been easy to describe. He often sided with the conservative justices in religious liberty, civil rights, and free speech cases, while joining the liberal justices in cases dealing with the LGBT movement and abortion, and placing new restrictions on capital punishment.

While he authored the majority opinion in Gonzalez v. Carhart and co-authored the plurality in Planned Parenthood of Southeast Pennsylvania v. Casey, where abortion regulations were upheld under the most deferential standard of review, he then joined the liberals in Whole Women’s Health v. Hellerstedt, requiring Texas to meet a higher standard of review for its commonsense regulation of abortion providers.

Likewise, he wrote for the majority in Fisher v. University of Texas at Austin in 2013, ruling that the university must prove that its use of race in admissions met the requirements of the Fourteenth Amendment’s equal protection clause. But when the case returned to the Supreme Court in 2016, Kennedy gutted his earlier decision and allowed the university to continue sorting students by race without defining its diversity goals or proving that race was necessary to meet its goals.

One common theme running through his jurisprudence in recent years is a concern for dignity and civility. This became evident in cases advancing the LGBT movement as well as protecting religious freedom. Indeed, though he authored the landmark case recognizing a constitutional right to same-sex marriage, this term he sided with Colorado baker Jack Phillips because of state officials’ hostility toward Phillips’ religious beliefs.

While he had a complicated relationship with conservatives, we thank Justice Kennedy for his service to our country and for giving President Trump a second chance to appoint a committed originalist to the Supreme Court.