Supreme Ct interprets Lautenberg Amendment
It's US v. Hayes. The question was whether to read the less than clear statute as requiring proof that the firearm possessor either (a) was convicted of a misdemeanor, whose elements were use of force, and against a household member, or (b) was convicted of a misdemeanor who element was use of force, with the government able to show in the firearm felony prosecution that it was in fact against a household member. (Defendant's underlying conviction was for generic battery, not specifically DV).
Majority, per Justice Ginsburg, goes for (b).
Roberts, joined by Scalia, dissents, going for (a). It's a straight statutory matter, Second Amendment neither briefed nor mentioned in either opinion.
UPDATE: courts got around the ex post facto problems by arguing (1) a violation of Lautenberg requires you to do something after its effective date, namely possess a gun and (2) as far as retroactively increasing the penalty for the DV charge, well, gun ownership is something like driver licensing or other such licensing, you can make licensing standards stricter without it being increased punishment for past acts.
I don't think (2) is viable in light of Heller. It's hard to see how stripping a person of a constitutional right, retroactively, for a misdemeanor, can't be seen as increasing the punishment for it.