  Precision measurements of anomalous quartic couplings of electroweak gauge
bosons allow us to search for deviations of the Standard Model predictions and
signals of new physics. Here, we obtain the constraints on anomalous quartic
gauge couplings using the presently available data on the production of
gauge-boson pairs via vector boson fusion. We work in the Higgs effective
theory framework and obtain the present bounds on the operator's Wilson
coefficients. Anomalous quartic gauge boson couplings lead to rapidly growing
cross sections and we discuss the impact of a unitarization procedure on the
attainable limits.
