  Coisotropic algebras consist of triples of algebras for which a reduction can
be defined and unify in a very algebraic fashion coisotropic reduction in
several settings. In this paper we study the theory of (formal) deformation of
coisotropic algebras showing that deformations are governed by suitable
coisotropic DGLAs. We define a deformation functor and prove that it commutes
with reduction. Finally, we study the obstructions to existence and uniqueness
of coisotropic algebras and present some geometric examples.
