"Why would a show trial or witchhunt be bad?"

So asked Chris Matthews of Frank Gaffney of the Center for Security Policy on today's edition of "Hardball." Gaffney was joined by liberal pundit David Corn of Mother Jones magazine in a segment around 5:20 p.m. ET and they were discussing the call by liberal Rep. John Conyers (D-Mich.) for a war crimes investigation of senior Bush administration officials and terrorist detainee interrogators.

For video of the exchange, click the play button on the embedded video.