The revelation that an upside-down American flag, a symbol adopted to contest Joseph R. Biden Jr.’s electoral victory, flew outside Justice Samuel A. Alito Jr.’s house in the days after the Jan. 6, 2021, attack on the Capitol raised questions about whether that had violated ethics rules.

The justice has said that his wife put up the flag in response to a neighbor’s anti-Trump yard sign. It remains unclear how long the inverted flag was on display outside his residence in Virginia.

It is the most recent disclosure about the Supreme Court to fuel concerns about impartiality and the appearance of bias.

Some of those controversies have involved Justice Alito. In June, he defended his decision to accompany a wealthy conservative billionaire on a luxury fishing vacation. That billionaire later had cases before the Supreme Court. In September, Justice Alito rejected demands for recusal in a major tax case after he gave interviews to one of the lawyers involved, David Rivkin, for The Wall Street Journal’s editorial page.

Here’s what to know.

Does the Supreme Court’s ethics code require Justice Alito to recuse himself from cases related to Jan. 6?

Ethics experts say there is not a clear-cut answer. That is in part because the justice said his wife had put up the flag, raising questions about whether the flag, and its symbolism, reflected his own views.

“It’s close,” said Amanda Frost, a law professor at the University of Virginia and ethics expert. “I certainly think it raises a question.”