Steven Lubet is a professor at Northwestern University Pritzker School of Law. His most recent book is " The 'Colored Hero' of Harper's Ferry: John Anthony Copeland and the War Against Slavery ." The opinions expressed in this commentary are his.

(CNN) Now that Neil Gorsuch has taken his seat as the 113th Supreme Court justice, his judicial life is going to change in many ways. One striking difference is he will no longer be subject to a written ethics code, as he was as a judge on the 10th US Circuit Court of Appeals. Although every other American court -- at both the state and federal levels -- has adopted some version of the American Bar Association's Model Code of Judicial Conduct , the justices on the nation's highest court have steadfastly refused to promulgate any such code for themselves.

While Supreme Court justices obviously face the same quandaries and dilemmas as all other judges, they alone have no set rules for resolving, or even addressing, ethics issues.

Members of Congress have repeatedly called on the justices to adopt an ethics code. Most recently, Sen. Chris Murphy, D-Connecticut, and Rep. Louise Slaughter, D-New York, introduced the Supreme Court Ethics Act of 2017, which would give the court six months to "promulgate a code of ethics" based on the Code of Conduct for US Judges already in effect for the lower federal courts, along with any modifications that "the Supreme Court deems appropriate."

At his confirmation hearing, Gorsuch said he had "no problem" continuing to abide by the conduct code for lower court judges, but he may soon find his new colleagues have different ideas.

Chief Justice Roberts has already made his own thoughts known on the subject, as he soundly rejected the idea of a Supreme Court ethics code in his 2011 Year-End Report on the Federal Judiciary

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There is no need for the court to adopt a "definitive source of ethical guidance," he said, because there are already numerous other sources and texts available to resolve ethics issues. Allowing that the code of conduct provides a good "starting point," Roberts continued that "no compilation of ethical rules can guarantee integrity."

Roberts' comments are fair enough, but they do not really explain the Supreme Court's opposition to adopting its own ethics code. The court's access to other sources of guidance, for example, holds true for every other US court, all of which have already adopted the Model Code of Judicial Conduct.

The same can be said of Roberts' observation that "no compilation of ethical rules can guarantee integrity." It is certainly true that codes, rules, statutes and even religious vows can all be broken, but they nonetheless play a crucial role in articulating society's expectations about our behavior.

Codes ranging from the Ten Commandments to municipal building regulations are violated every day -- thus failing to guarantee integrity -- but only an avowed anarchist would consider them unnecessary.

At the Supreme Court level, in any case, the function of an ethics code is not to guarantee integrity, and even less to compel compliance or punish violations -- the latter of which would be impossible, given that the justices enjoy life tenure and cannot be disciplined short of impeachment.

Instead, the objective of a code would be to set discernible standards for the justices' conduct so that the public could know the norms to which the justices are holding themselves.

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It is true, as the chief justice also pointed out, the existing code of conduct for lower court judges "does not adequately answer some of the ethical considerations unique to the Supreme Court." But that is why the Supreme Court Ethics Act allows for whatever "amendments or modifications" the court deems necessary.

The fine details of an eventual Supreme Court code of conduct are relatively unimportant, so long as the ethics rules are definitive. The public cannot truly know what to expect of the justices until they tell us precisely what they expect of themselves.