Congress also passed a bill in 2013 reversing some of the disclosure requirements that it had established and celebrated just one year before. The original bill, for example, mandated the creation of a searchable online database of trades by members and aides. The 2013 law made it harder to identify wrongdoing, allowing members of Congress to submit disclosures in a form that is not easily searchable.

And the narrow ban on insider trading does not go far enough. Members still may be tempted to cast votes that are personally profitable but not in the public interest. And because insider trading is a very difficult crime to prove, it is likely that they still have ample opportunity to profit from their privileged positions.

As if to underscore these problems, members continue to buy and sell shares in companies that have business before Congress.

Senator James Inhofe, the Oklahoma Republican who chairs the Armed Services Committee, bought stock in the defense contractor Raytheon last year while pushing for an increase in federal spending on defense. The senator said the decision was made by a financial adviser, and after its public disclosure, he said he would make no further investments in the industry.

Inhofe’s declaration of abstinence amounts to a tacit acknowledgment of the need for stronger rules that apply to all members of Congress. Public Citizen and other groups have argued for a narrow rule barring members from trading in the shares of companies that have business before their committees. Such a rule, however, would not go far enough. The work of Congress encompasses the entirety of the economy.

The most comprehensive solution would be to require people who are elected to Congress to divest holdings in public companies within a reasonable period following their election. But such a requirement could impose significant costs on people entering public service. It would be nearly as effective, and less burdensome, to bar members from buying or selling shares.

A bill that would impose such a ban was introduced earlier this year by Senator Jeff Merkley, Democrat of Oregon, and Senator Sherrod Brown, Democrat of Ohio. It would require members to put holdings in blind trusts, or else to refrain from any trading until they leave Congress. The bill also would bar members of Congress from serving on corporate boards.

These are necessary reforms, and they are long overdue.