Do the US courts consider Wikipedia reliable? According to lawyer-blogger Evan Brown,

...[I]t is interesting to note that in the past year or so several courts, including more than one federal circuit court, have cited to it to fill in background facts relevant to cases before them.

[... examples snipped...]

At least one court, however, has noted the risk of error in relying on an open source project, and refused to consider what Wikipedia had to say. The Tennessee Court of Appeals noted:

Given the fact that this source is open to virtually anonymous editing by the general public, the expertise of its editors is always in question, and its reliability is indeterminable. Accordingly, we do not find that it constitutes persuasive authority. [English Mountain Spring Water Co. v. Chumley, 2005 WL 2756072 (Tenn.Ct.App., October 25, 2005).]

The English Mountain court apparently took this whole notion of reliability pretty seriously. It wouldn't even take Wikipedia's word for it that "bottled water" is a "beverage."