Mtetwa received her LLB (Bachelor of Laws) degree from the University of Botswana and Swaziland in 1981. She spent the next two years working in Swaziland as a prosecuting attorney (a lawyer who is responsible for starting legal cases against people accused of crimes). In 1983, she moved to Zimbabwe. There she worked as a prosecutor until 1989. That year, she went into private practice (a professional business that is not controlled or paid for by the government). She began to limit her business to one subject, the practice of human rights law. In one of her more famous cases, she questioned a section of Zimbabwe's law, the Private Voluntary Organizations Act. She won the case. The law allowed the government to change the group of people who manage or direct non-governmental organizations. She also questioned the results of 37 districts in the parliamentary elections. In a PBS documentary, Mtetwa said the reason for her activism is "not because there is any glory or cash to it and not because I'm trying to antagonize the government... I'm doing it because it's a job that's got to be done".