Can a tattoo be a witness?  Felon Michael Greer was convicted of illegally possessing a firearm and ammunition.  On appeal to the Second Circuit, he argued the government's use of a tattoo on his left arm to link him to the car in which the ammo was found violated his Fifth Amendment right against self incrimination.  The court determined:

The government relied on the tattoo not as an "identifying physical characteristic" but for the "content of what [was] written." The tattoo was therefore testimonial and, because it linked Greer to the ammunition, incriminating.

But wait...

The voluntary tattooing of an incriminating word to Greer's arm was . . . not the product of government compulsion.  In the absence of compulsion, Greer's Fifth Amendment claim fails.

(citations omitted)   

Hat tip to How Appealing.