[CSB]

Depending on the jurisdiction, criminal charges can be "dismissed" "withdrawn" "no true bill" (by a grand jury) "nolle prosequi (by the district attorney)" "not referred" (to a court-martial by a convening authority) and so on.

Those are all ways of saying "the government is not going to prosecute you for the alleged crime, you are free to go."

In some cases, once that decision has been made, it cannot be revoked, even if more evidence comes up later (or if you confess) the case cannot be revived.

One example: A case dismissed by the judge during trial, at the close of the state's (weak) case, upon the Defendant's motion for judgment of acquittal. The constitutional prohibition on double jeopardy bars a retrial, even if the government later comes up with more proof than it had the first time.

Another: A Defendant is kept in pretrial confinement for two years awaiting trial, while the prosecution uses court days for "more important cases." By the time the Defendant finally comes up for his trial, his defense witnesses have died, disappeared, moved out of range of a subpoena, or key physical evidence (like telephone records or recordings of 911 calls) have been erased or written over. The judge, on motion of the Defendant, may find that the Defendant's right to a speedy trial has been violated -- and cannot be salvaged -- and since the Defendant cannot ever get a fair trial, dismiss the charges.

In each of those cases, the dismissal is "with prejudice." That is, it is literally "pre-judged" in favor of the Defendant without a trial. The case can never be brought back again. Whether guilty or not, the Defendant is released to "go forth and sin no more."

On the other hand, cases can be dismissed for technical reasons. For example, foreman of the grand jury forgot to sign the indictment. The prosecutor in a state case might elect to dismiss charges against a bank robber in state court because the federal government is going to prosecute the Defendant in federal court. Those dismissals are "without prejudice" and the case against the Defendant can be brought back to life for trial, usually by going back to the grand jury and having them return a new indictment.

So all the government did in the terrorism case is turn over the case files to the civilian side of the house, but announced to the courts and the Defendant's "If for any reason you cannot be tried in a civilian court, we reserve the right to take the case files back again and try you by a commission."