Mr Tanczos, who lost ' />
Green Party MP Nandor Tanczos followed the Maori Party's lead by inserting "Treaty of Waitangi" into the oath of allegiance.
Mr Tanczos, who lost his seat at the election, but returned to Parliament to fill the vacancy caused by party co-leader Rod Donald's death, was sworn in yesterday.
Maori Party members stood as Mr Tanczos read out his pledge to the Treaty and Crown. They, last week, tried to swear allegiance to the Treaty of Waitangi, but repeated the correct oath when asked.
Mr Tanczos was asked to repeat the oath omitting the Treaty reference - but was applauded when he added "also" to the end, implying his first pledge still stood.
The Green MP was not the only one to break the rules - Maori Party MP Hone Harawira broke more rules than he followed.
When MPs ask questions in Parliament they are not allowed to digress but Mr Harawira prefaced a question, in Maori, praising Mr Tanczos for swearing to the Treaty.
He also greeted supporters in the gallery.
Speaker Margaret Wilson interrupted him for a translation and then corrected Mr Harawira on procedure.
She also told him that in future he should sit when the Speaker speaks.
Finally he asked his question - on TVNZ's charter and commercial roles.
Mr Tanczos' first action as Mr Donald's replacement was to launch a petition against getting rid of glass milk bottles in the South Island that Donald had initiated.
New Meadow Fresh milk owner billionaire Graeme Hart is rumoured to be planning to axe the 25,000 a day reusable bottles.
Mr Tanczos asked Environment Minister David Benson-Pope to be the first to sign the petition and he replied that he would consider it.