What is the state of the law on witness testimony in civil cases?

This was an eye-witness, invested with "built-in credibility." McCreary v. Sigler, 406 F.2d 1264, 1269 (8 Cir.), cert. denied, 395 U.S. 984, 89 S.Ct. 2149, 23 L.Ed.2d 773 (1969); cf. United States v. Acarino, 408 F.2d 512, 514 (2 Cir.), cert. denied, 395 U.S. 961, 89 S.Ct. 2101, 23 L.Ed.2d 746 (1969). He pointed out to the officer that there was at that very time a car parked across the street; there was a person seated in that vehicle; that person was armed; that he had a pistol at his waist and had narcotics in his possession.