“Binding Code of Ethics” for the U.S. Supreme Court?

Sorry, but I don’t get this.

Clarence Thomas voted to block evidence of his wife’s criminality.  Please don’t tell me we need a “binding code of ethics” to cover something so obviously illegal and corrupt.

The Due Process clauses of the United States Constitution require (emphasis mine) judges to recuse themselves from cases in which there is a strong possibility that the judge’s decision will be biased.

Do we need a new law that makes it illegal to kill someone with a spear-gun?  Of course not.  The deliberate and unlawful killing of another person is always called “murder.”