WASHINGTON (Reuters) - Pivotal votes cast by U.S. Chief Justice John Roberts in abortion and death penalty cases have underscored his new standing as the Supreme Court’s ideological center and the outsized role he may play in major rulings for years to come.

FILE PHOTO: U.S. Supreme Court Chief Justice John Roberts arrives for the swearing in ceremony of Neil Gorsuch as an associate Supreme Court Justice in the Rose Garden of the White House in Washington, U.S., April 10, 2017. REUTERS/Joshua Roberts/File Photo

Roberts, a genial 64-year-old conservative appointed in 2005 by Republican President George W. Bush, sided with the nine-member court’s four liberals on Thursday night in blocking a restrictive Louisiana abortion law from taking effect. He also sided on Thursday night with the four other conservative justices in allowing the execution of a Muslim convicted murderer in Alabama.

His vote in the abortion case was particularly noteworthy because it represented a turnaround from his vote in a 2016 abortion case in which he had joined two other conservatives in dissent when the Supreme Court ruled 5-3 to strike down similar regulations targeting abortion doctors in Texas.

The role of Supreme Court swing vote had been filled by Justice Anthony Kennedy, who sided with its liberal bloc on divisive issues including abortion and gay rights before retiring last July. Following Republican President Donald Trump’s appointment in the past two years of Justice Brett Kavanaugh, who replaced Kennedy, and Justice Neil Gorsuch, Roberts now appears to be the most centrist of the five conservative justices who make up the court’s majority.

“He’s now the center, and the center has moved to the right,” American Civil Liberties Union lawyer Jennifer Dalven said.

Most court-watchers expect Roberts to side with his fellow conservatives on a wide range of issues including business disputes, challenges to Trump’s actions and divisive social issues beyond abortion.

Roberts takes his institutional role seriously and is a defender of the federal judiciary at a time when Trump often criticizes judges and accuses the courts of political motives. As chief justice, the federal judiciary’s highest-ranking judge, Roberts presides over oral arguments in cases before the court and leads private meetings among the justices.

During an appearance on Wednesday at Belmont University College of Law in Tennessee, Roberts spoke of the “great responsibility” that comes with the job.

“You do kind of have to keep in mind that it’s a modest - important, but modest - role,” Roberts added.

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MORE ABORTION CASES

The court on Thursday granted an emergency application by Shreveport-based abortion provider Hope Medical Group for Women to stop Louisiana’s law from taking effect. The justices, however, did not rule on the merits of the case.

The Supreme Court is now likely to take up the clinic’s appeal of a lower court ruling allowing the law, with a decision on the merits possible in 2020, just months before the U.S. presidential election. Whether Roberts will oppose the Louisiana abortion restrictions as well as others pursued in conservative-leaning states remains an open question.

Trump, seeking re-election next year, has seized on the abortion issue, which appeals to his conservative base and evangelical Christian voters who are among his most ardent supporters. Trump on Tuesday urged U.S. lawmakers in his State of the Union address to pass legislation banning late-term abortions.

The court will decide soon whether to hear Indiana’s bid to revive a state ban on abortions performed due to the sex or race of the fetus or evidence of disability. Indiana this week asked the Supreme Court to hear another abortion case concerning a law to require fetal ultrasounds before abortions take place.

Those cases do not turn on the 2016 precedent, meaning Roberts may feel less inclined to side with the liberals.

“I think it’s still quite likely that he will be voting and casting a fifth and decisive vote to uphold a variety of abortion regulations that fall short of outright prohibitions,” Cornell Law School professor Michael Dorf said.

The court has a handful of major cases during its current term, which ends in June, that will test to what extent Roberts differs from Kennedy on key issues. The court on Feb. 27 will hear arguments in a religious rights dispute about a towering cross standing on public land in Maryland.

Kennedy and Roberts likely would not differ on that issue. In 2010, both were in the majority when the court ruled that a cross on federal land in the Mojave National Preserve in California could remain, upholding the government’s decision to transfer the land into private ownership.

The court’s action on the death penalty case was an example of Roberts siding with his fellow conservatives in allowing Alabama to execute death row inmate Domineque Ray, who said that as a Muslim his constitutional religious rights were violated by the state’s refusal to let him have an imam present. The state allows inmates to be accompanied by a Christian chaplain but not clergy representing any other religion.

The court rejected his request for an imam’s presence, prompting liberal Justice Elena Kagan to call the decision “profoundly wrong.”