  We revisit the interpretation of earlier low temperature experiments on
Josephson junctions under the influence of applied microwaves. It was claimed
that these experiments unambiguously established a quantum phenomenology with
discrete levels in shallow wells of the washboard potential, and macroscopic
quantum tunneling. We here apply the previously developed classical theory to a
direct comparison with the original experimental observations, and we show that
the experimental data can be accurately represented classically. Thus, our
analysis questions the necessity of the earlier quantum mechanical
interpretation.
