There doesn't seem to be any evidence that the ANV expressly target free blacks or knowingly kidnap free blacks into slavery during the Gettysburg Campaign. However, had the Confederate Army taken free blacks, they would have been acting within U.S. Federal law. Under the provisions of the Fugitive Slave Law of 1850 a free black caught by slave catching patrols had no real recourse in law according to Section 6 which reads, " In no trial or hearing under this act shall the testimony of such alleged fugitive be admitted in evidence; and the certificates in this and the first [fourth] section mentioned, shall be conclusive of the right of the person or persons in whose favor granted, to remove such fugitive to the State or Territory from which he escaped, and shall prevent all molestation of such person or persons by any process issued by any court,judge, magistrate, or other person whomsoever. "

After 1850, the decks were stacked to the point of creating a virtually irrefutable presumption that a black caught by a slave catcher was a fugitive slave unless the black was fortunate enough to have some sort of proof of their "free" status.