In People v. Washington , Washington claimed he was prevented from presenting a defense in his criminal case (wherein he was alleged to have been engaged in the "criminal sale of a controlled substance"), because he had been denied the ability to challenge the testimony of two undercover cops who were using aliases.
Washington's counsel had requested that the officers' true names be disclosed so that their testimony in other cases could be reviewed and possibly utilized to impeach their credibility in this case. Failing that, Washington's counsel argued that his constitutional "right of confrontation" would be violated.
Both the New York County Supreme Court, and the Appellate Division, First Department, didn't think the denial of that request was such a big deal, since the officers' shield numbers had been provided and, because the officers hadn't used their true names in other cases, the disclosure of their identities in this instance would have "had no discernible practical value."
While we understand the need to protect the identity of our police officers, particularly in sensitive investigations and prosecutions, one has to admit the process is still quite scary
One reader noted:
You can't easily check a cop's testimony in other cases. One good way to find out about a cop is to go through the Civilian Complaint Review Board (CCRB) . You can get CCRB stuff with a badge number only. But most judges won't sign subpoenas for the CCRB without a good reason to do so, the CCRB isn't too helpful anyway (they rarely discipline), and most prior stuff about a cop is inadmissible at trial.
So, if our reader is correct and badge numbers are worthless, how are a defendant's due process rights safeguarded in these kinds of criminal cases?

It's everybody else we're worried about.