In this article we consider a simple model for a c–axis Pb/YBa2Cu3O7−δ Josephson junction. The observation of a nonzero current in such a junction by Sun et al. [A. G. Sun, D. A. Gajewski, M. B. Maple, R. C. Dynes, Phys. Rev. Lett. 72, 2267 (1994)] has been taken as evidence against d–wave superconductivity in YBa2Cu3O7−δ. We suggest, however, that the pairing interaction in the CuO2 planes may...
