The new Supreme Court ethics code released on Monday looks good on paper, experts in legal ethics said. But only on paper.

Its lack of an enforcement mechanism means that it will operate on the honor system, with individual justices deciding for themselves whether their conduct complies with the code. That makes it a parchment promise, some experts said, without transparent procedures for assessing whether it has been violated or consequences when it has.

“The primary problem is how to give these rules teeth, especially in light of the fact that there have been repeated violations of these very rules,” said Amanda Frost, a law professor at the University of Virginia.

Among those violations, she said, citing news reports, were participation in fund-raising events and the failure to disclose gifts by Justice Clarence Thomas and the use of Supreme Court staff members to help sell books by Justice Sonia Sotomayor.