Where does the well-regulated militia part come in?

As the U.S. Attorney in Boston for the past several years, Michael Sullivan has gotten mixed reviews from me, but as the temporary head of the Bureau of Alcohol, Tobacco and Firearms he seems to be doing a pretty good job. Maybe too good for some people. A while ago I read that the two Idaho senators, Larry "I'm resigning no I'm not" Craig and Mike Crapo are opposing his confirmation as the permanent head because the ATF is already too aggressive in enforcing gun laws.

Mmmmmkay.

Then today I read this on the Boston Globe's editorial page:

( copyright violation but I don't care )

I surely don't want to inconvenience those poor, picked-on gun dealers, as I'm wondering where next week's school shooting is going to take place.

. . .