Let $M$ be a compact 3-manifold with boundary equipped with a 1-dimensional foliation all of whose leaves are circles. An old theorem of Epstein says that $M$ is a Seifert fibered space.
The proof of Epstein’s theorem is quite complicated, and it predates the modern theory of 3-manifolds centered around Thurston’s work and geometrization.
Question: Are there any alternate proofs now of Epstein’s theorem?