Now that we're, uh, budding experts on pot look-alikes, this one is too easy, too crude by half.
False Hemp is a huge—to eight feet high, six across—perennial for huge borders like this one, or for to-the-front focal statements in smaller plantings when you want to razz the cops.
At a glance (or if you're toked up already), there is something druggy or at least doubtful about False Hemp.

The feathery pinnate leaves are attractive, you have to admit. But aren't they smokeable? Or at least a bit too "native" for proper gardens? I don't know about the smoke-ability, but they sure aren't those of pot, which (we now know) are palmate instead—all the leaflets attach at the same point, like your fingers to your palm. False Hemp leaves are "pinnate" instead: all the leaflets attach to a long central spine.
Well what about those buds? They're suspicious for sure.
Wrong again: they lengthen into a veritable curtain of greenish whatevers.
Pot flower clusters stay distinctly upright, unlike pot users of course.
(Thank you www.Crocus.co.uk for the pair of full-flowered pix. We can always count on our fellow plant-geeks across the pond to be up on everything possible in the garden.)
But one thing you are right about: False Hemp is native of one of those druggy "stans": Pakistan. Guilt by association anyone?
Another druggy muddle here: that common name "False Hemp". Hemp is Cannabis sativa sativa is , a close cousin of the smokeable stuff, Cannabis sativa indica, but without the active ingredient to make smoking it worth the trouble. Police take note: It would be self-incriminating let alone embarrassing to get riled up over datisca: Would you be thinking datisca were pot because you were so buzzed already you couldn't tell the difference? Or just so ignorant you couldn't tell the difference?
If ever there were a latin name to use with complete innocence, at full volume, it's that of False Hemp: Datisca cannabina. Say it loud, say it proud: "duh-TISK-uh cuh-NAB-in-uh". As in: "Oh that? That's my Datisca cannabina. Lovely isn't it? So delicate—and so under-used." And then, a tisk-tisk-tisk will let everyone know that you, at least, are up to the challenge of bringing this unaccountably scarce and rarely-seen plant to wider reknown.
Last off-kilter detail: Crocus.co.uk gives a common name for datisca of "Bastard Hemp." Leave it to the Brits to work in the improper heritage angle too.
PS: I myself will be using Datisca in my vast Yellow Borders, when the economy picks up enough that I can convince myself, let alone my husband, that another $50 K spent on the garden is just the wise decision to make.