  Vector boson scattering is a well known probe of electroweak symmetry
breaking. Here we study a related process of two electroweak vector bosons
scattering into a vector boson and a Higgs boson ($VV \rightarrow Vh, V=W,Z$).
This process exhibits tree level interference and grows with energy if the
Higgs couplings to electroweak bosons deviate from their Standard Model values.
Therefore, this process is particularly sensitive to the relative sign of the
ratio of the coupling between the Higgs and the $W$ and $Z$, $\lambda_{WZ}$. In
this work we show that a high energy lepton collider is well suited to study
this process through vector boson fusion, estimate the potential sensitivity to
this ratio, and show that a relatively modest amount of data can exclude
$\lambda_{WZ} \simeq -1$.
