CP Studies of the Higgs Sector: A contribution to the LHC/LC Study Group document

The CP structure of the Higgs sector will be of great interest to future colliders. The measurement of the CP properties of candidate Higgs particles will be essential in order to distinguishmodels of electroweak symmetry breaking, and to discover or place limits on CP-violation in theHiggs sector. In this reportwe briefly summarize various methods of determining the CP properties of Higgs bosons at different colliders and identify areas wheremore study is required. We also provide an example of a synergy between the LHC, an $e^+e^-$ Linear Collider and a Photon Collider, for the examination of CP-violation in a Two-Higgs-Doublet-Model.