In Brazil, knowledge (or lack of knowledge) of the 'Brazilian language' was a relevant factor in identifying illegalities in the introduction of blacks as slaves after the prohibition of trafficking, enacted by the Law of 7 November 1831, which penalized offenders with the release of all blacks who landed in the country after this date.  
To curb fraud, the law was regulated by the Decree of 12 April 1832, which ordered the authorities to carry out an immediate linguistic examination to check 'whether [the recently arrived African] understands the Brazilian language' (Chalhoub, 2015, pp. 15-16). The use of the Portuguese language thus became a fundamental element in investigating clandestine trafficking.