Anomalous damping of electrons (or holes) distinguishes cuprate superc
onductors from ordinary metals. Electron-electron scattering yields th
e unusual linear variation of the damping with temperature T and frequ
ency omega, providing that the susceptibility exhibits scaling in omeg
a/T, as in the case of a nested Fermi surface. The opening of an isotr
opic energy gap of s-wave symmetry is shown to yield distinctive devia
tions from scaling of the susceptibility which produce characteristic
decreases in the damping below the superconducting transition temperat
ure. We obtain a conductivity peak using a nesting approximation and f
ind agreement with microwave experiments close to T(c).