  It will be shown that a pronounced interfacial pair breaking can be
identified in Josephson tunnel junctions provided the first j_{1c} and the
second j_{2c} harmonics of the supercurrent, as well as the depairing current
in the bulk j_{dp}, are known. Namely, within the Ginzburg-Landau theory a
strong interfacial pair breaking results in the relation
j_{2c}j_{dp}>>j_{1c}^2, while in standard junctions, with negligibly small pair
breaking, the relation of opposite character takes place.
