In his recent perspective piece, What if Mueller Hadn’t Been Appointed? (N.Y.L.J., July 31), Joel Cohen observes that matters would have been worse if the investigation into President Trump had not been conducted by special prosecutor Mueller but rather by an ordinary line prosecutor, the hypothetical James Straight.

True. But matters would have been better if the investigation had been conducted by a true independent counsel, call her Jane Arrow, appointed on the model of the post-Watergate statute that Congress passed in 1978.

Not being bound by the constitutional views of the Justice Department, Ms. Arrow could, like her predecessors Leon Jaworski and Kenneth Starr, have reached an independent conclusion as to whether the President is immune from indictment. If, like them, she had concluded that the answer is “no,” she could then have exercised prosecutorial discretion as to whether to pursue that route.

She would then have been able to write a straightforward report rather than one Mr. Cohen correctly describes as “reading like a Russian novel … filled with double negatives.”

The reason this did not happen is that the prior statute—which the Supreme Court upheld on a 7-1 vote in 1988—worked too well. Republicans were roiled by the Iran-Contra investigation. Democrats fumed when Mr. Starr’s inquiry into Whitewater expanded to include potential perjury by President Clinton about his relationship with Monica Lewinsky.

Under cover of the impeachment investigation into President Clinton, and over the warnings of commentators like myself that they were acting shortsightedly, the parties colluded to allow the independent counsel statute to expire in 1999.

Congress should on a bipartisan basis now correct its bipartisan mistake and enact a new independent counsel statute.

Eric M. Freedman is Siggi B. Wilzig Distinguished Professor of Constitutional Rights at Maurice A. Deane School of Law at Hofstra University.