  In this paper, we attach an $L_\infty$-algebra to any coisotropic submanifold
in a Jacobi manifold. Our construction generalizes and unifies analogous
constructions by Oh-Park (symplectic case), Cattaneo-Felder (Poisson case),
L\^e-Oh (locally conformal symplectic case). As a new special case, we attach
an $L_\infty$-algebra to any coisotropic submanifold in a contact manifold. The
$L_\infty$-algebra of a coisotropic submanifold $S$ governs the (formal)
deformation problem of $S$.
