  We review the recent measurements of the current-phase relation in cuprate
Josephson junctions. Special attention is paid to 45 degree grain boundary
junctions and to c-axis junctions between YBCO and Nb. It is shown that the
anomalous properties of such junctions which have been found experimentally
(large second harmonic of the current phase relation, sign change of the first
harmonic as a function of temperature) are qualitatively consistent with the
d-wave symmetry of pairing in the cuprates. It is argued that in order to
describe the data quantitatively, quantum fluctuations of the order parameter
need to be taken into account. It is pointed out that the Josephson effect is
an ideal tool for measuring the reduced phase stiffness in the cuprates.
