U.S. directs agents to cover up program used to investigate Americans
Let's not get too carried away.  Secrecy in law enforcement can be a valuable tool: it allows things like protection and development of informants, lawful surveillance, undercover operations, etc.<p>Prosecutors have never been required to turn over ALL evidence -- only exculpatory evidence (and that does not include evidence that might be useful in jury nullification, only evidence that would tend to prove the accused innocent of the charges).  Withholding evidence of guilt from the defence is common: it is done to protect sources and ongoing investigations or even to shorten a trial.  If you have more than enough to convict, why trot everything out?<p>The described "parallel" investigation is another common technique.  If you have a source of evidence you need to protect, then you develop different evidence and instead use that to secure the conviction.  Provided the evidence used is real and is sufficient to prove guilt, no laws or moral codes have been transgressed.<p>Law enforcement and prosecutors use inadmissible evidence all the time to pursue an investigation.  The point of an investigation is to secure sufficient admissible evidence to successfully convict (prove guilt of) the perpetrator.  But the rules don't say you can't use all the information at your disposal -- only that some of it might not be useful for you at trial.  (Full disclosure: there are, and should be, rules governing what law enforcement and other state and federal agencies can do in collecting evidence.  But disclosure of all information, evidence, and techniques to the defendant is definitely not one of them.)<p>An interesting corollary is the so-called "fruit of the poisonous tree" problem.  If a critical piece of evidence is deemed inadmissible, it might take with it a bunch of other evidence that was generated based upon it. Courts frequently permit the prosecution to re-introduce some of the evidence if  it can be shown that it could have (not "was", "could have") been developed without access to the inadmissible piece.  This is precisely the parallel development narrative described, and it is a very common tool.<p>I agree that this particular system seems well beyond the pale, but lets not pretend that suddenly getting rid of secrecy in law enforcement and removing prosecutorial discretion is a no-brainer solution.  Lets also not pretend that this isn't a clear extension of standard practice (albeit a pretty major and troubling extension we might want to trim back a bit).