  We apply the bosonization technique to the problem of tunneling in a Fermi
liquid, and present a semiclassical theory of tunneling rates. To test the
method, we derive and evaluate an expression for the tunneling current in the
problem of two parallel Luttinger liquids. Next we study tunneling between
parallel two dimensional Fermi liquids. In the absence of a magnetic field, the
conductance $I/V$ has a resonance peak at zero bias. Our estimate for the peak
broadening agrees with the many-body theory results. In a magnetic field
perpendicular to the plane, we find a tunneling gap linear in the field, in
agreement with the experiment. In this regime the tunneling is spatially
coherent over a distance of the order of the cyclotron radius. The coherence
can be probed by a magnetic field parallel to the plane, which gives an
Aharonov-Bohm phase to the tunneling amplitude. As a result, the current is an
oscillatory function of the field.
