What Is The "Waiver" Nonsense?

[ThomWV]

Reading in another damming article about Rove just a few moments ago I ran across this statement:

"Cooper testified on his conversations with Rove under court order before the grand jury to avoid going to jail, and had received a last-minute waiver from Rove allowing him to break a confidentiality pledge."

It seems to me patently absurd that any sort of waiver was required to allow someone to comply with a lawful order to testify before a court. A Private contract between Rove and Cooper is certainly no bar to a Grand Jury's proceedings.

So what is this nonsense about a waiver? People act like its means something when it doesn't seem to me to be of any importance at all.