Brazil is betting big on gambling after nearly a century of restrictions, upping the ante for law firms to guide players in the sector on how to do business in one of the world’s largest and most complex economies.

President Luiz Inácio Lula da Silva signed a law in December that regulates fixed-odds betting in Brazil, where online wagers have flourished in a gray area since sports bets were legalized in 2018—undoing a prohibition in place since the 1940s.