Eric Holder, explaining why he has a "vast amount" of discretion in how the Justice Department prosecutes federal law, veers into self-justifying gibberish:
“There is a vast amount of discretion that a president has — and, more specifically, that an attorney general has,” Holder responded. “But that discretion has to be used in an appropriate way so that your acting consistent with the aims of the statute but at the same time making sure that you are acting in a way that is consistent with our values, consistent with the Constitution and protecting the American people.”
"Consistent with the statute" but also with "our values" and "the Constitution" and the goal of "protecting the American people"? Sounds like a hell of a balancing act, which he could probably more simnply and accurately describe as "when we find it politically advantageous."
I've seen a lot of prosecutors in my time, and certainly they have all exercised discretion in which laws they purse vigorously and which they don't. But it's usually a matter of pragmatics. If you have a lot of burglaries going on, and are faced with limited time and manpower, it makes sense to put a lot of effort there and not so much in stopping, say, marijuan smoking or prostitution.
At the highest level, when the wishes of the White House get involved, it's probably safe to assume the decision is almost always political. Yes, I know every attorney general has done something I would probably consider abuse of power, but, as in other areas, this administration knows how to go biger and bolder than everyone else, without shame or remorse.