The Supreme Court has never said that if the prosecutor fails to provide a target notice to grand jury witness, and that witness is later indicted, the indictment is invalid. Here is Section 9-11.151" of the U.S. Attorney's Manual:

The Supreme Court declined to decide whether a grand jury witness must be warned of his or her Fifth Amendment privilege against compulsory self-incrimination before the witness's grand jury testimony can be used against the witness. See United States v. Washington, 431 U.S. 181, 186 and 190-191 (1977); United States v. Wong, 431 U.S. 174 (1977); United States v. Mandujano, 425 U.S. 564, 582 n. 7. (1976). In Mandujano the Court took cognizance of the fact that Federal prosecutors customarily warn "targets" of their Fifth Amendment rights before grand jury questioning begins. Similarly, in Washington, the Court pointed to the fact that Fifth Amendment warnings were administered as negating "any possible compulsion to self-incrimination which might otherwise exist" in the grand jury setting. See Washington, at 188.

Notwithstanding the lack of a clear constitutional imperative, it is the policy of the Department that an "Advice of Rights" form be appended to all grand jury subpoenas to be served on any "target" or "subject" of an investigation. See advice of rights below.

In addition, these "warnings" should be given by the prosecutor on the record before the grand jury and the witness should be asked to affirm that the witness understands them.

Although the Court in Washington, supra, held that "targets" of the grand jury's investigation are entitled to no special warnings relative to their status as "potential defendant(s)," the Department of Justice continues its longstanding policy to advise witnesses who are known "targets" of the investigation that their conduct is being investigated for possible violation of Federal criminal law. This supplemental advice of status of the witness as a target should be repeated on the record when the target witness is advised of the matters discussed in the preceding paragraphs.

If you're interested in reading the Advisement of Rights, it's at the same link. Basically, it's a Miranda warning.

So what does this all mean? In a nutshell, Fitzgerald may be planning on indicting Karl Rove; he doesn't have to tell Luskin; if he chooses to tell Luskin, he doesn't have to do it by letter; you can bet Fitzgerald will orally provide Rove with advisement of rights once he's in the grand jury room .

My take: Luskin is taking a giant risk in sending Rove in to testify again. I don't think Luskin would take this risk unless he was convinced Rove was going to be indicted: Either Rove convinces the grand jury he didn't commit a crime - or Rove gets indicted on a few more counts. It's a shot at winning the whole ball of wax - while risking a few more years in jail, if that.

What it also says to me is that Fitzgerald hasn't offered Rove any deal he's prepared to accept. And now I don't think Rove is going in to sell anyone else out. I think Rove is going in to try and clean up his prior mis-statements or lies, whichever they were.

Question: What does Rove want to correct the record on? His conversations with Matthew Cooper? Or something to do with the plan of the White House Iraq group to discredit Joseph Wilson by outing his wife? Your ideas?

Update: The AP reports:

Before accepting the offer, Fitzgerald sent correspondence to Rove's legal team making clear that there was no guarantee he wouldn't be indicted at a later point as required by the rules.