Beers made with hemp, specifically with marijuana, are part of homebrewing lore. There are tales of hop vines grafted onto cannabis roots in attempts to produce innocent-looking but psychoactive hops (it doesn't work), of beers with marijuana or hashish replacing some of the hops at some point during brewing (supposedly, dry-hopping with roasted leaves is simple and effective).
At present, commercial brewers in the U.S. who want to add hemp to their beers without breaking the law are stuck with using hemp fiber or hemp seeds (killed by roasting or other means) -- nothing else is legal. Fiber would be ludicrous (a length of rope in each bottle?), so seeds, as found in bird feed or at your neighborhood health-food store, are the only choice. What's better for brewing, the whole seeds or the residue from extracting the oil, I can't say.
Hempen Ale (the name is a trademark), "ale brewed with hemp seeds," is "a
classic brown ale with a twist." The seeds, the label goes on, give it
a "creamy head" and "mellow herbal flavors and aromas." There's a blurb
on the uses of hemp and its seeds, with medicinal and recreational uses
notably absent. The label's border is of blurry leaves not clearly those
of cannabis, and the faint image in its background is a scene, somehow
familiar, of diminutive fairy-folk and quaffing frogs. Perhaps the beer's
website explains (I never look at such sites before finishing a review).
The beer is a clear warm brown -- either the seeds clear the beer or make excellent filtration a must -- with a short, dense head that endures, a little of it remaining to the last sip. It smells of dark malt, slightly of hops, and of nothing else I can detect. A robust bitterness prevails from the start of every sip: bittering hops, dark malt, and...something. The hop bitterness decays to a faint malty sweetness, with that odd taste always present and forming the aftertaste. It's herbal, yes, but I can't pin it down. Friend and The Net Net colleague AjD says that in another hemp-seed beer the herbal taste reminded him of flaxseed, but I've eaten a lot of whole flaxseed in my day (in "Uncle Sam" cereal) and to me it tastes very different. This taste is bitter, almost aromatic, not quite as medicinal as saffron's, not like the gentian extracts found in some bitters; it's not quite like that of any herb I'm familiar with. Maybe people who snack on hemp seeds (or hash brownies?) will find it familiar and welcome, but I don't find it "mellow" or particularly pleasant, and it keeps me from pinning down any of the subtle tastes of alcohol or flavoring hops. At least it keeps the maltiness well in check.
Hempen Ale is a curiosity. Without the hemp seeds it would be a tasty brown ale, competently made; with them, it tastes unusual and, to me, not worth drinking. Try it if you're feeling adventurous. I expect to see a pesto-flavored beer next, and I expect I'd like that better.