Most banknotes have traces of cocaine on them; this has been confirmed by studies done in several countries. In 1994, the U.S. 9th Circuit Court of Appeals determined that in Los Angeles, out of every four banknotes, on average more than three are tainted by cocaine or another illicit drug. Additionally, paper money in other parts of the world show a similar drug contamination, and studies indicate that they might even serve as a vector of disease, though researchers disagree over how easily diseases are transmitted this way.