Here are 4 times Justice Kennedy's swing vote saved the country from ruinous conservative rulings

Republican Supreme Court Justice Anthony Kennedy, who was appointed by Ronald Reagan 30 years ago, will retire.

That means that it's very likely Donald Trump will be picking his replacement.

Kennedy's nickname is "The Decider" and while he has not been a reliable ally to the left—for example supporting Trump's travel ban, helping Republicans curtail voting rights and busting public sector unions—he has been much more amenable than some of his fellow Republican colleagues.

Kennedy cast the deciding vote to legalize gay marriage.

In 2015, Kennedy authored the opinion in Obergefell v. Hodges, legalizing gay marriage nationwide. He did so with a memorable opinion that closed with a paragraph that reduced some to tears.

No union is more profound than marriage, for it embodies the highest ideals of love, fidelity, devotion, sacrifice, and family. In forming a marital union, two people become something greater than once they were. As some of the petitioners in these cases demonstrate, marriage embodies a love that may endure even past death. It would misunderstand these men and women to say they disrespect the idea of marriage. Their plea is that they do respect it, respect it so deeply that they seek to find its fulfillment for themselves. Their hope is not to be condemned to live in loneliness, excluded from one of civilization’s oldest institutions. They ask for equal dignity in the eyes of the law. The Constitution grants them that right."

Kennedy supported affirmative action by casting the deciding vote to uphold a race-based admissions plan at the University of Texas.

The case, Fisher v. Texas, was brought by a white Texas woman who claimed she was rejected from the University of Texas at Austin based on her race. Fisher, nicknamed #BeckyWithTheBadGrades, did not succeed with Kennedy. In his majority opinion, Kennedy considered the university's options for an admissions policy that promoted its values and found that it was doing the best it could by rejecting Fisher.

Kennedy struck down a Texas law that severely restricted access to abortion.

The severely restrictive law was done based on "safety" of the women, and Kennedy was not buying it.

In the case, Whole Woman’s Health v. Hellerstedt, he was sympathetic to women who had to drive hundreds of miles to obtain abortions and to arguments citing the lack of medical evidence justifying restrictions.

At the time of the decision, which outraged Republicans, they reminded their supporters of the stakes of the 2016 election.

“Today’s disappointing decision is another reminder of what’s at stake in this election and why we can’t afford to let Hillary Clinton win,” said Reince Priebus, then the head of Republican National Committee.

Republicans took heed, while Democrats did not.

He helped protect the First Amendment right to burn a flag.

Strange as it sounds, there was once a case in which four U.S. Supreme Court justices wanted to restrict the right to burn an American flag in protest.

In the case, a man named Gregory Lee Johnson burnt a flag during a protest at the 1984 Republican National Convention in Dallas. He was sentenced to a year in prison and fined $2,000 for the act, before eventually winning his freedom at the Supreme Court thanks in part to Kennedy.

Every time you see an American flag burning at a protest, you can thank Anthony Kennedy for securing our freedom.