Because Massachusetts slaves were considered both as property and as persons before the law, slaves could institute and prosecute lawsuits in the courts against their master (the defendant) who would be obliged to demonstrate their lawful title to ownership of their slave. By 1780, nearly thirty slaves had sued their master for their freedom, most during the years following 1764. However, these cases were not decided on the basis of any "natural right" to freedom; instead, the courts required a specific point of law to decide in favor of a slave, such as a master's broken promise to grant freedom, or the questionable slave status of the individual's mother.