I'm thinking that the number of "Gun to victim's head; we need secrets from $Corporation_Name now!!!" situations which a typical small police dept. would actually experience, even over a decade, is ~ZERO. And the chance that a small police dept. would have the skill set, familiarity with the procedure, etc., so that they could correctly request the right data, from the right part of the right corporation, is about the same.

SO - move the power to make such requests up to (say) State Police departments, or even somewhere in the DHS. Those guys have (or should have) sufficient resources to secure their e-mail, staff call-back phone lines 24/7, etc. And in the other direction, they should be far better able to vet alleged local police officers who contact them with emergency requests.