Siaosi graduated from the University of Auckland in 1999, then worked in Rarotonga as a Corporate Attorney specialising in trusts in several jurisdictions including onshore US trusts administered under US State Tax laws.
After an OE through North, Central and South America, he returned to New Zealand and graduated in 2009 with a Masters in Law (Honours), specialising in Commercial Law. Siaosi has been working in the Treaty claims area since 2009 and has been involved in numerous historical inquiries including Te Rohe Potāe, Taihape ki Rangipo, Te Paparahi o Te Raki and the North East Bay of Plenty. Siaosi also assists clients within Kaupapa Inquiries where his focus is on Māori Military Veterans and Housing Policy & Services.
Siaosi also has experience in trust administration, Māori land law matters and Marine and Coastal Area Act applications in the High Court.