Can a witness be called to testify at trial?

only to the opposing party and when the witness has a relationship with the opposing party that would in a pragmatic sense make his testimony unavailable to the opposing party regardless of physical availability."); Schoenberg v. C.I.R., 302 F.2d 416, 420 (8th Cir. 1962) (internal citations omitted) ("We have serious doubt whether in a situation such as is presented here, where the witness was apparently equally available to both parties, any presumption should flow from the failure of either party to call such witness. Any rule creating a presumption from failure to produce a witness must be applied with caution.").