Ps filed a lawsuit against Ds, manufacturers of blood products infected with HIV. The suit was certified as a class action and D filed a for a writ of mandamus as an order certifying a class is not a final decision within the meaning of 29 U.S.C. Section 1291. P advanced two theories of liability in that had the blood products companies taken adequate precautions against Hepatitis B, Ps would have also been protected against the more deadly HIV virus and that when Ds did hear of the HIV virus, they negligently dragged their feet in screening donors. The district judge looked at the logistics of certifying the class under these two theories and thought that a special verdict was in order so that if no negligence were found under either theory, that presumably would end all cases. If the special verdict found negligence, this would then leave individual members free to file individual tort suits using the special verdict with the doctrine of collateral estoppel to block relitigation of the issue of negligence. D opposed this and filed for a writ of mandamus.