Constructive possession, taken to its limit, is the theory that everyone with a rifle and a hack saw possesses a SBR.
That's ONE example of the legal theory of constructive possession. It's important to understand that, as a legal concept, it encompasses multiple scenarios. The biggest mistake non-lawyers make when discussing constructive possession in the firearms context is thinking that it has something to do with "constructing" a firearm.
In the legal context, it doesn't mean "relating to construction." It means "implied by operation of law" and is an antonym to "actual."
This plays out in several ways. But let's just use some examples to clarify. (And bearing in mind that for every case, because this is an attenuated theory, there's always going to be a defense argument that there WASN'T constructive possession. I'm just using common, hopefully obvious, examples of where courts have found there was. Different courts don't always find the same ways even with similar facts.)
Guns:
1) Joe is holding a rifle with a stock and a 12" barrel that isn't registered with the ATF. This is
actual possession of an illegal SBR.
2) Joe has a rifle with a stock and a 12" barrel that isn't registered with the ATF. It's under his truck's seat when he's pulled over, but he isn't holding it. This is
constructive possession of an illegal SBR because he has the ability to exercise dominion and control over the illegal SBR.
3) Joe has an AR15 lower receiver with a stock in his garage on the workbench. Joe also has a 12" barreled upper receiver underneath the workbench in a box. These are the only AR15 parts he owns. Joe posted on a local gun forum, "Screw the ATF. I'm gonna make me an SBR and I ain't registering it!" Joe has
constructive possession of an illegal, unregistered SBR. (Not every example of constructive possession will require these elements, but what hurts Joe here is his obvious intent to make an illegal SBR, and possessing components in close proximity with no other legitimate purpose.)
These theories don't just apply to Joe and his guns. They apply to all sorts of contraband. When Joe gets to jail, he meets his cellmate, Walter, who doesn't like guns. He likes drugs.
1) Walter gets arrested with some methamphetamine in his pocket. Walter has
actual possession of methamphetamine.
2) Walter, driving around alone, gets pulled over and the cops search his car. In his glovebox, there's a packet of methamphetamine. Walter has
constructive possession of the methamphetamine because he had the ability to exercise dominion and control over it. (And unfortunately for his defense attorney, there's no passenger to try to pin it on instead.)
3) Walter is in his RV when the cops bust in. They don't find any methamphetamine, but there's a cook underway. Walter has all the ingredients to make methamphetamine and has started the process, but not finished it. It could be argued that Walter has
constructive possession of methamphetamine.
Now... in light of the last drug example, there's some good things we can talk about. In drug cases, most states would not charge Walter with possession of methamphetamine in the last case. It would be hard to make the charge stick because there's no actual meth yet. So many state legislatures have gotten clever and made some new laws to fight the explosion of meth use. For instance, manufacturing methamphetamine is a separate crime in Kentucky, and doesn't require a finished product. Possession of methamphetamine precursors is also a crime. If you have some plastic tubing, some coffee filters, and some lithium batteries in your actual possession, you can get convicted of possession of meth precursors if the jury believes you intended to make meth.
How does that relate to guns? Well, everyone gets worried about whether you should have an extra part (lower, upper, stock, etc) for an AR15 around because of the risk of prosecution for constructive possession of an unregistered SBR. But that's a very rare type of prosecution. It's hard for the ATF to prove their case, and they aren't running around kicking in doors looking for this situation. If you have lots of different guns and extra parts, will a jury really believe that you meant to make an SBR? If you're an average Joe, probably not. And if you've already applied for a tax stamp, then your lawyer can easily argue to the jury that you never intended to make an SBR
until it was legal for you to do so. Hard to get a conviction that way. The guy who gets convicted is the guy with criminal underworld connections who has a small assembly line in his shop with lots of pieces that could be made into a machine gun, but haven't been yet. Just because the ATF had the misfortune to raid on the day that he doesn't have a machine gun built, doesn't mean they can't get a conviction based on constructive possession. A jury will buy that.
Generally, we shouldn't worry about
that theory of constructive possession. Instead, we should worry about when we allow people to exercise dominion or control over a registered NFA firearm that they're not legally allowed to possess. If I have a nice glass-front gun cabinet and I leave my short-barreled shotgun in it, then that's fine as long as I'm home. But if it's owned individually by me, and I leave to go to the store while my wife stays home, then there's the potential for her to be charged with possessing an SBS that's not registered to her, under a theory of constructive possession.
That's what OP is trying to avoid, and although the likelihood of he or his roommates being charged is low, it's still a risk, and one that he's smart to avoid.
Aaron