We now know that the Justice Department granted immunity to at least five of Hillary Clinton's close aides during the FBI's investigation of her email scam.  However, it's hard to understand, in light of the ultimate disposition of the case, why Justice gave these people immunity.  Representative Jason Chaffetz, whose committee has the herculean task of cleaning the Augean Clinton State Department stables, revealed the previously unpublicized immunity deals.  He was quoted as saying of them, "[N]o wonder they couldn't prosecute a case" referring to the FBI and Justice Department.

In fact, in normal circumstances, Chaffetz is exactly wrong.  Immunity deals are granted precisely to prosecute a case and, in the absence of utter corruption, would never be issued unless prosecutors had other more valuable targets they intended to put away in return for letting some of the smaller fry go.  That this did not happen in the Clinton email case is another factor that makes the decision so utterly fraught.

Just as unusually, the five immunized witnesses apparently were not required to cooperate with federal authorities or with Congress in return for their deals, other than providing a limited amount of immunized information.  In the case of Mills and Samuelson, it was evidently their laptops.  Clinton apologists insist that in return for partial cooperation, the witnesses were granted only limited immunity.  Even assuming that this was true, the FBI never acted thereafter in any way, shape, or form to put these witnesses at risk of prosecution.  Incredibly, they were permitted to share joint counsel (so that each knew what was being asked of the others during FBI interviews), and both Mills and Samuelson, immunized witnesses in the case, were permitted to attend Hillary's July interview by the FBI and join her gaggle of attorneys!

All this raises the question of why the Justice Department granted immunity at all.  If, as it now seems certain, neither the Justice Department nor the FBI had any actual interest in investigating the case with the object of filing criminal charges against Hillary or her legion of aides there would be little or no apparent reason to grant anyone immunity.  You don't need the cooperation of witnesses involved in a criminal conspiracy if you have no intention of unwinding that conspiracy and prosecuting those behind it.

Here is one halfway coherent solution.  In the autumn of 2015, the FBI investigation of Hillary's home-brew email server gained some steam as it became apparent that she had deceived the State Department, the FBI, and the public as to the nature and extent of her document mishandling and destruction enterprise.  It also raised the extremely serious possibility that even more was going on besides a massively corrupt and illegal attempt to hide potentially embarrassing personal documents that tied Hillary to pay-for-play schemes, money-laundering, and influence-peddling related to the Clinton Foundation.  With her private server and upwards of 30,000 emails professionally destroyed (allowing little or no recovery), the FBI had to put to bed the possibility of deliberate espionage – that is, whether Clinton, her aides, or all of them were also involved in a massive foreign spy operation.  

The Justice Department apparently granted Brian Pagliano, Clinton's chief I.T. guy in charge of setting up and shutting down the server, limited immunity in December 2015, the others sometime thereafter. 

It is now abundantly clear that Comey and his minions within the FBI were willing to live with typical Clinton venality and corruption.  But counter-espionage is probably the FBI's most important function, and Comey could not ignore what must have appeared to be the very real prospect that Hillary was running or had been duped into running a serious and treasonous foreign intelligence scheme against the U.S. government.  For the FBI to overlook this, should it turn out to be true, would threaten not only the country, but obviously the careers and livelihoods of Comey and his boss, Loretta Lynch.  Plus, Comey's evidently quite successful suppression operation against dissent within the FBI to his philo-Clinton shenanigans would probably become unmanageable if the Clinton server, the email destruction, the lies, and the secrecy were mostly or in part facilitating a deliberate foreign intelligence penetration of the U.S. government, as opposed to run-of-the-mill Clinton corruption.   

Thus, the FBI had to get to at least a scintilla of the truth in the case, enough to assure itself that Hillary's scheme was merely another case of Clintonian vice, and that Hillary and her aides had not become outright agents of a hostile foreign power.  In order to figure this out, they needed to talk to the key players, which explains the immunity deals and the people chosen – those closest to Hillary and with the most connection to the email destruction, where critical evidence of foreign involvement would have been most evident.

It is also quite likely that Comey and Lynch let Bill and Hillary Clinton know that the immunity deals were not a way of delving into their corrupt practices or to establish grounds for prosecuting the same, but rather to reassure the government that there was nothing else going on.  Either that or the unusual nature of the deals themselves made that clear.  That explains the equanimity of the Clinton camp during the FBI probe right up to the end. 

When Comey declined to charge Clinton, he explicitly rejected the possibility that espionage was behind the email scheme, something he could not vouch for unless his agents had convincingly determined that such was not the case.  He implied that the servers were probably hacked, but this fell into Comey's broad definition of "extreme carelessness," which he used to improperly and dishonestly exonerate Hillary of prosecutable crimes.

Comey satisfied himself and his boss Lynch that Clinton was not a foreign agent engaged in active espionage against the United States, and having done that, he wasn't interested in pursuing the matter further, no matter how many other crimes the scheme involved.  In that regard, the immunity grants served their purpose, both for the FBI and Hillary.  And if Hillary is so inclined, this presents a great campaign slogan: "Hillary – Dishonest and corrupt, but only for herself."