  The Cauchy problem for the scalar wave equation in the Kerr geometry is
considered, with initial data which is smooth and compactly supported outside
the event horizon. A time-independent energy estimate for the outgoing wave is
obtained. As an application we estimate the outgoing energy for wave-packet
initial data, uniformly as the support of the initial data is shifted to
infinity. The main mathematical tool is our previously derived integral
representation of the wave propagator.
