"One of the things that amazes me in this place is that there really is a lack of practical
understanding of the separation of powers.
"Sometimes the courts overstep the mark with Parliament when they go too far with parliamentary privilege."
Finlayson, who was watched on by a crowd in the public gallery that included his mother and former National prime ministers Sir Bill English and Jim Bolger, acknowledged former party leaders and prime ministers Sir John Key and English.
He mentioned Labour MPs past and present including Dame Winnie Laban, Dame Annette King, Paul Eagle, Paul Swain and Rick Barker and Dame Fran Wilde.
But one person who did not get a mention in his final speech was current National leader Simon Bridges.
Bridges was caught on tape earlier this year talking with now disgraced MP Jami-Lee Ross about MPs the party could afford to lose. Finlayson was among those named.
But Finlayson did pay tribute to his "talented" National caucus colleagues, singling out Gerry Brownlee for his time as a minister overseeing the aftermath of the Canterbury quakes and the Christchurch rebuild.
"When the history of the Key government is written, his work rebuilding a shattered city will be regarded as that Government's greatest achievement. I witnessed in Cabinet his absolute commitment to and his compassion for his fellow Cantabrians."
He also acknowledged Nikki Kaye for her "grit, courage and determination" in overcoming cancer and in her work as an Opposition MP.
Finlayson signed off with "I'm very pleased to be going, but grateful I've had the opportunity to serve.
"That's all from me. If anyone needs a lawyer in the future, don't bother me. All the best. goodbye."
Finlayson, a born and bred Wellingtonian, has a law degree from Victoria University. He worked in law for 25 years before entering Parliament and it is to law he will return.
Finlayson was came into Parliament in 2005 as a list MP and served mostly as attorney-general and Treaty Negotiations Minister, overseeing 59 deeds of settlement with iwi.