Maddie is a criminal prosecutor. She also undertakes disciplinary and regulatory prosecutions. Her experience to date includes acting in prosecutions for the Crown, Police, Ministry of Social Development, Inland Revenue Department, Teaching Council of Aotearoa New Zealand and Maritime New Zealand. She has been seconded to the Medical Council of New Zealand, Police Prosecution Service, Teaching Council of New Zealand, and the Ministry of Justice working on the Christchurch Masjidain Attack Inquiry.
Maddie holds the classification of Intermediate Crown prosecutor. She has prosecuted serious offending on behalf of the Crown including sexual violence, drug dealing, violence and serious fraud. She regularly appears in the District Court. To date, Maddie has prosecuted 30 trials. She has prosecuted jury and judge-alone trials as the lead Crown prosecutor in the District Court. She has represented the Police and Crown on appeals in the High Court and Court of Appeal.