Many states do not in fact have a structured school inspection system that could enforce such a ban. The United States, for example, has one of the largest student bodies in the world but the state does not have a formal inspection system that could enforce a ban on homework. Therefore any ban would only prove a recommendation at best, and could not possibly hope to be enforced.  Furthermore, even in those states that do have inspection bodies, the regularity of inspections allows school principals to prepare for their arrival. Students might be forced by their teachers to lie to inspectors, otherwise they would receive even more homework. Furthermore, the school inspections are partly so that they can test the ability of students – therefore teachers are encouraged to give their students homework so that they do better on these inspections.