Story highlights Court watchers have been looking for signs Justice Anthony Kennedy will resign

Kennedy, 80, swore in his former clerk, Neil Gorsuch, as the newest justice Monday

He has been a key swing vote on issues such as abortion and affirmative action

(CNN) With Justice Neil Gorsuch sworn in and the Supreme Court's 422-day era-of-eight over, attention has turned to Anthony Kennedy, the jurist who administered Gorsuch's oath at the White House ceremony and on whose key vote the law in America has long turned.

Justice Kennedy, 80, has been mulling retirement. Former law clerks and others close to him say he is privately vowing to step down in the next few years. The centrist conservative is the court's most vacillating, agonizing, justice, and he is likely balancing his oft-voiced sense of judicial mission with the realities of age.

Whether he will leave this summer when the current term ends, or continue serving, is not easy to predict. But it will matter.

Kennedy has cast the decisive vote on high-profile cases for more than a decade, upholding abortion rights, ensuring campus affirmative action, and declaring the constitutionality of same-sex marriage. In recent years, he has moved to the left on racially inflected disputes, casting the key fifth vote for broad federal coverage against housing bias in 2015, and new constitutional protection against racism in jury deliberations just this March.

As evident in his brief remarks in the Rose Garden Monday, Kennedy speaks in exalted terms about America's constitutional democracy. He is equally earnest about his individual role, routinely asking himself, he says: "Why am I about to rule the way I am about to rule?"

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