After being outlawed for more then a century, the wormwood-based liquor absinthe is once again being legally manufactured and sold in America, sort of.
Recent studies have demonstrated that absinthe's reputed hallucinogenic effect, which had lead to its ban almost a century ago, are purely the psychosomatic effect of absinthe drinkers' expectations. As a result of the studies, absinthe bans in many countries have been overturned outright. (Switzerland even amended its constitution to legalize the stuff. A few of the more rational countries, including Great Britain, Australia, and, surprisingly, Spain, Portugal, never banned the stuff in the first place.)
Is outright legalization the case in the U.S.? Unfortunately not. (America isn't a country often willing to admit its mistakes.) For the time being, U.S. sales are limited to absinthe that can be shown to contain less than 10 parts per million of thujone -- which is the ingredient from wormwood that the studies have shown to be non-hallucinogenic.
For reference, nearly half the weight of sage oil, a dietary supplement commonly used to boost short-term memory, is thujone -- however sage oil is perfectly legal in the U.S. What is the effect of thujone that justifies the continued restriction on absinthe? Supposedly reduced attention span.