We show that there is only one
obstruction to isotoping an essential lamination ℒ in a 3-manifold M containing an
essential torus T so that when both ℒ and M are split open along T, the resulting
lamination ℒ|T is essential in the split open manifold M|T. This is the existence of a
cylindrical component in ℒ. This generalizes previous results relating taut foliations
and essential tori.