Consider the following premises. For all x, x is a lawyer if and only if x is a politician. For all x, if x were a politician, then x is a lawyer. There is at least one x for which if x were a lawyer, then x is a politician. Can we infer the following from them? If we can, name the inference rule being used: For all x, the fact that x were a lawyer does not imply that x is a politician.
That contradicts the premises. Therefore the answer is no.