You have the right to confront an actor against you.

Another "terror" trial and another set of witnesses allowed to testify in disguise.  From the Herald:

The federal government’s secret informant and undercover agents who helped catch a suspected Key West terrorist last summer may testify at trial using fake names and even disguises, a judge has ruled.
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Two FBI agents and one confidential informant “may testify under their undercover pseudonyms at trial without disclosing their true identities,” Magistrate Judge Lurana Snow wrote in an Aug. 17 ruling. “The defense shall be prohibited from asking any questions seeking personal identifying information from or about [them].”
Also, the witnesses may enter and leave the courthouse from a non-public doorway and their voices and pictures may not be publicly disclosed through any recordings or images, Snow ordered.