The U.S. Supreme Court is set for a rightward swing that could lead to sweeping changes to some of the most explosive culture-war issues roiling the country: a roll-back or abolition of abortion rights, the expansion of the death penalty and limits to programs that help minorities attend university.

Justice Anthony Kennedy announced his departure on Wednesday. In a court with four liberal judges and four conservatives, Justice Kennedy, a moderate right-winger, often cast the deciding vote in some of the country’s most contentious cases. President Donald Trump is expected to nominate a more conservative replacement, giving the right a five-four majority.

Mr. Trump said he wants to move “as quickly as possible” and that he is considering 25 contenders.

“We will begin our search for a new justice of the United States Supreme Court. That will begin immediately,” he told reporters in the Oval Office on Wednesday afternoon, shortly after a half-hour meeting with Justice Kennedy, 81.

Mitch McConnell, leader of the Republican majority in the Senate, said legislators would confirm Mr. Trump’s court pick this fall, before the Democrats get a chance to take control of the Senate in midterm elections.

“It is imperative that the President’s nominee be considered fairly and not subjected to personal attacks,” Mr. McConnell said.

The court legalized abortion with its decision in Roe v. Wade in 1973. Justice Kennedy co-wrote the decision in a 1992 case, Planned Parenthood v. Casey, that reaffirmed abortion rights and pushed back against state attempts to restrict them.

Justice Kennedy’s retirement gives Republicans the opportunity to fulfill their promise to install a majority on the court that would overturn these decisions.

“Abortion rights are going to be reined in, if not eliminated,” said Sam Erman, an associate professor of law at the University of Southern California, who clerked under Justice Kennedy.

Exactly how – and to what extent – would depend on the laws that states pass and which of them are appealed to the top court. State legislators have taken different approaches over the years, from limiting the circumstances in which women can have abortions, to limiting how abortions may be performed, to piling on hurdles that women must go through.

Justice Kennedy also favoured limits on the death penalty, writing the court’s opinion in the 2005 Roper v. Simmons case, a five-four decision that barred executions for crimes committed by people under the age of 18. And he backed some limited use of affirmative action – allowing the race of minority applicants to count in their favour in university admissions – writing the court’s opinion in Fisher v. University of Texas, a 2016 case.

A more right-wing court could take different views on these issues.

Justice Kennedy’s departure also comes at a time when some business owners are refusing to serve same-sex couples, and university campuses, and conservative groups say attempts by left-wing students to create safe spaces have stifled freedom of speech.

Then-president Ronald Reagan nominated Justice Kennedy for the court in 1987, as a compromise figure after the Senate rejected his previous nominee, right-winger Robert Bork.

Justice Kennedy’s decisions fell on both sides of the court’s ideological line. He sided with conservatives on campaign finance – writing the 2010 Citizens United decision that gave free rein to third-party groups to run attack ads in elections – and gun rights, voting in favour of striking down a ban on handguns in Washington. Earlier this week, he backed a decision to uphold Mr. Trump’s ban on travel by citizens of five Muslim-majority countries.

He sided with the court’s four liberal justices on same-sex marriage: He wrote several rulings expanding marriage rights, including the 2015 decision that legalized same-sex marriage throughout the country.

Barbara Perry, a presidential scholar at the University of Virginia, said same-sex marriage is unlikely to be overturned, because public support has expanded to the point that no state would attempt to challenge it.

“The country is moving in the direction of supporting it – that’s where history is taking us,” she said. “Anthony Kennedy kept the court up to date with where society was moving.”

Ms. Perry, who got to know Justice Kennedy during a year studying the Supreme Court in the 1990s, said his moderation will be particularly missed.

The battle over control of the court has become particularly intense in recent years. The Republican Party refused to allow the Senate to consider president Barack Obama’s nominee for the previous vacancy, moderate Merrick Garland.

Instead, Mr. McConnell, delayed until after the election of Mr. Trump, allowing another conservative, Neil Gorsuch, to replace Mr. Scalia.

The Globe and Mail, June 27, 2018