It is one thing, experts in legal ethics said on Friday, for the spouse of a Supreme Court justice to express political views, even ones shot through with wild conspiracy theories. That may not by itself require the justice’s recusal from cases touching on those views.

But the text messages from Ms. Thomas, a longtime conservative activist who goes by Ginni, revealed something quite different and deeply troubling, experts said.

The messages from Ms. Thomas to Mark Meadows, President Donald J. Trump’s chief of staff, sent during and just after the fraught weeks between the 2020 presidential election and the Jan. 6 attack on the Capitol, demonstrated that she was an active participant in shaping the legal effort to overturn the election…

“When your spouse is conversing with people who have some control over litigation to challenge an election,” [Amanda Frost] said, “you shouldn’t be sitting on the Supreme Court deciding that election or any aspect of it.”