Mary Trump, the estranged niece of Donald Trump, recently shared online what she sees as a major threat following the Supreme Court's presidential immunity ruling.

"My greatest fear before the decision on presidential immunity was handed down was not that the justices would grant absolute immunity to whomever occupied the Oval Office but that they would, as they did in Bush v. Gore, use a sledgehammer and a scalpel to benefit only Donald Trump," she wrote Thursday in a Substack post.

Last week, the Court issued its ruling in response to Trump's claims of presidential immunity after his federal indictment for election interference, among other criminal cases against him.

In a 6-3 decision, the Court said former presidents have absolute immunity for official acts but no immunity for private acts. The Court sent back the case, which was brought by Department of Justice special counsel Jack Smith and focused on Trump's efforts to overturn the 2020 election results, to a lower court in Washington, D.C., to figure out what constitutes an official act.

The Court's decision overturned a February appeals court ruling that rejected Trump's presidential immunity claims. The three-judge panel of the U.S. Court of Appeals for the District of Columbia Circuit found that immunity does not apply to Trump because he is no longer president.

It's possible Trump, who maintains his innocence, will still face trial for charges in the case if some of the acts in the indictment are not deemed official. But his supporters see the ruling as a victory because it makes it less likely the case will go to trial before the November election.

"BIG WIN FOR OUR CONSTITUTION AND DEMOCRACY. PROUD TO BE AN AMERICAN!" Trump wrote in a Truth Social post following the ruling.

Newsweek reached out to Trump's spokesperson via email for comment.

Mary Trump has been a longtime critic of her uncle. In her Thursday post, she said the Court's decision bestowed "upon him not only heretofore unthinkable power but also retroactively and prospectively making it impossible to hold him criminally accountable for anything."

She continued: "We're going to have to remind the Supreme Court and my uncle, who really has the power in this country. We need to dump some metaphorical tea in the metaphorical harbor and declare our independence from the ignorant, cruel and dangerous right-wing zealots who are on a mission to strip our rights and our country away from us."

In another Substack post, she expressed another one of her fears ahead of the election.

"The only thing scarier than the idea of my uncle being in the Oval Office again is the idea of the Republicans controlling the Senate and the House of Representatives," she wrote.