You can see that in US. (seemengly) they focus into the state, when it comes to traffic codes/laws regulation/rules.

    http://public.findlaw.com/traffic-ticket-violation-law/state-traffic-law/

In Brazil, I think it is more federal, albeit counties have your say (today even traffic tickets are being issued by county law-enforcers).

   http://www.infolegis.com.br/legbrasileiraassunto-tuvxz.htm

Traffic

The oldest Brazilian traffic legal instrument dates back to 1910. Later on further legislation was enacted. The first Traffic Code was established in 1941. It was replaced in 1966 by the new National Traffic Code (CNT), established by Act n. 5108, 1966. In the following year this Code was substantially altered by Decree-Law n. 237, 1967.

////////////

  To me, there´s no 'escola de legislação' (I don´t know if there´s some branch of it in

law school)

   What I have read is, there are driving schools (cursos de formação de condutores, antiga auto-escolas), in which the subject is taught.  They teach Brazilian traffic legislation (the National Traffic Code), first aid, driving practice, parking and others subjects as well.

  www.scielo.br/pdf/reeusp/v42n4/en_v42n4a20.pdf

I hope it helps, and let´s wait the experts to QC-pass this answer.