Before winning the presidential election, Donald Trump had said he would “strongly consider” overturning the Supreme Court’s decision to give same-sex couples the right to marry.

With a vacancy on the Supreme Court, Trump has said he would like to appoint a Supreme Court judge ideologically aligned with late conservative Judge Antonin Scalia, who died in February. Three judges who voted to legalize same-sex marriage — Ruth Bader Ginsburg, Anthony Kennedy and Stephen Breyer — are 83, 80 and 78, respectively. In his nine-page dissent on the June 2015 ruling by the Supreme Court on Obergefell vs. Hodges, Scalia wrote, “To allow the policy question of same-sex marriage to be considered and resolved by a select, patrician, highly unrepresentative panel of nine is to violate a principle even more fundamental than no taxation without representation: no social transformation without representation.”

“ Donald Trump had said he would “strongly consider” overturning the Supreme Court’s June 2015 decision to give same-sex couples the right to marry. ”

Marriage equality was widely regarded as the last frontier for gay-rights activists. In June 2014, the Supreme Court overturned the 1996 Defense of Marriage Act, opening up federal benefits to same-sex married couples, but state-level benefits were still in limbo in the 13 states that ban same-sex marriage, including Michigan, Ohio, Kentucky, Florida and Tennessee. Overturning the Supreme Court decision would mean that spouses (and children) in same-sex families might not be eligible for federal health care or company health insurance provided by their spouse’s plan, and same-sex married couples would have to pay federal inheritance tax if one spouse left money to the other.

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Gay-rights activists say it would take a complex confluence of events to challenge the June 2015 ruling. “If Trump meets the first condition of changing the makeup of the court, there then would need to be a conflict on the issue of same-sex marriage that would compel the court to revisit the issue,” Chris Johnson, chief political and White House correspondent for the Washington Blade, a D.C.-based lesbian, gay, bisexual and transgender newspaper, wrote in that paper. “One possibility is a state could decide to defy Obergefell and pass a law barring or inhibiting marriage rights for gay couples. Such a measure already failed just two months ago in Tennessee.” (In June 2015, the Supreme Court ruled 5 to 4 that the ban on same-sex marriage was unconstitutional.)

“ If Trump meets the first condition of changing the makeup of the Supreme Court, there then would need to be a conflict on the issue of same-sex marriage that would compel the court to revisit the issue. ”

The gift tax is another area that was made easier for same-sex couples with the Supreme Court ruling last year. A married couple can give away $28,000 without incurring a federal gift tax penalty versus $14,000 for a single person. That’s an advantage for couples where one partner is wealthy and wants to avoid federal estate taxes, experts say. With the Supreme Court ruling, spouses in same-sex couples are also eligible for Social Security benefits, and they will be covered under the survivor benefits rule for both defined contribution and defined benefits plans.

If the law was overturned, same-sex couples would no longer be allowed to file federal tax returns using the “married filing jointly” or “married filing separately” options in order to receive state-level spousal tax breaks and benefits. In Arkansas, Michigan and Mississippi, where same-sex marriage was previously not recognized at a state level before the June 2015 ruling, there was no conformity between federal and state taxes, so same-sex married couples have to file taxes as if they are single, says Carol Calhoun, an attorney at Venable law firm in Washington, D.C. And that does not account for the damage to the perceived legitimacy and social acceptance of same-sex relationships.

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Not everyone believes Trump would attempt to undo the Supreme Court decision through his judicial appointments. “At his core, I don’t think Donald Trump cares about marriage equality. “Meaning, I don’t think it bothers him,” says Crystal Broyles, a program manager in Bentonville, Ark., who recently married her partner of eight years. “However, he partnered up with a man who cares very deeply about LGBT discrimination. If it weren’t for Mike Pence, I wouldn’t be concerned about LGBT issues and the Trump Administration at all. The next four years are a mystery, but we are resilient, we are strong, and we will continue to fight for equality and freedom.”

“There will be additional issues related to marriage equality, such as businesses that want to discriminate against same-sex couples,” says Brett Ward, a partner in law firm Blank Rome’s matrimonial practice group in New York. There have been a slew of so-called religious freedom bills winding their way through the courts in various states. They could allow a baker or even a hotel or restaurant to refuse service to a same-sex couple on religious grounds. “People will have less choice,” he says. “Those issues are brewing now. They may or may not change the current status quo, but certainly the respect and dignity that everyone should be treated equally.”