Dubbed the "anti-joking law", the relic of Brazil's 1964-1985 dictatorship prohibits ridiculing candidates in the three months before elections.
Critics say the ban threatens free speech and is a blight on the reputation of Latin America's largest nation.
"Do you know of any other democracy in the world with rules like this?" asked Marcelo Tas, the acerbic host of a weekly TV comedy show that skewers politicians and celebrities alike.
"If you want to find a bigger joke, you would have to look to Monty Python."
Proponents say the restrictions keep candidates from being portrayed unfairly, help ensure a level playing field and encourage candour by those seeking to replace centre-Left President Luiz Inacio Lula da Silva.
Making fun of candidates on air ahead of elections is punishable by fines up to £72,000 and a broadcast licence suspension.
Print and the Internet are not covered by the ban. The article doesn't say what happens if a candidate simply makes an ass of himself.