In Eliashberg-Thurston's famous paper "Confoliations" Corollary 3.2.11, they proved that Irreducible three manifold with $b_{1}>0$ admits semi-fillable contact structure using Gabai's theorem in the paper ''Foliations and the topology of 3-manifolds'' about the existence of the taut foliation. But it seems that they require the foliation to be $C^{2}$ while I can't find this $C^{2}$ regularity in Gabai's paper. (Gabai showed that if $H_{2}$ is not generated by spheres and torus, then we can assume the foliation to be $C^{\infty}$.) So my question is why can they use Gabai's theorem in this case?