Appointment to the United States Supreme Court is an extraordinary honor that conveys the power to influence the course of American law and justice. It does not seem too much to ask that sitting justices order their personal financial affairs to minimize the potential for conflicts of interest requiring them to sit out cases.

That long-simmering problem led to a big embarrassment last week when financial and personal conflicts affecting four Supreme Court justices left the court without a quorum. It was thus unable to rule on whether to hear an appeal arising from a controversial lawsuit against American companies that did business in apartheid-era South Africa. Participation of six of the nine justices is necessary for the court to conduct business.

The absence of a quorum automatically affirmed a lower court ruling allowing the lawsuit to move forward. The court did not give reasons for the recusals by the four justices. Three of them  Chief Justice John Roberts and Justices Samuel Alito Jr. and Stephen Breyer  own stock in some of the defendant companies, according to a report in The Times on May 13. A son of the fourth justice, Anthony Kennedy, works for one of the firms. The court’s inability to proceed was unusual. Solitary recusals resulting in a 4-to-4 deadlock are a more common occurrence.

Federal law requires judges to disqualify themselves from cases if they own even a single share of stock in a company that is a party in a case, a policy important for preserving the appearance and reality of fair adjudication. Plainly, the public would be better served if justices put their money in mutual funds, government securities or certificates of deposit instead of inviting conflicts by investing in publicly traded companies with matters coming before the court.