Terris was first elected as the member for Western Hutt in. He became the opposition spokesperson on broadcasting; until he aroused the ire of the Left by saying that there should also be a private channel, and was accused of "political incorrectness". So he was made the party spokesman on "Internal Affairs", a shadow portfolio generally reserved for "caucus down-and-outs". In 1984 he was not selected for Cabinet but was given the "consolation prize" of Deputy Speaker, and Chairman of Committees of the House of Representatives from 1984 to 1990. In May 1990 Terris submitted a private members bill to force a binding referendum on the electoral system. His bill was defeated but a referendum eventually occurred in 1992. In January 1986 he was convicted of drink-driving, something he told The Evening Post was "not a sensible thing to do". Terris represented the Western Hutt electorate until 1990, when he was defeated by National's Joy McLauchlan, one of a number of losses contributing to the fall of the Fourth Labour Government.
Terris later served as the Mayor of Lower Hutt between 1995 and 2004 as an Independent. He is the only person ever to have been both MP and Mayor in the Hutt Valley.
Outside politics
An ordained Anglican priest, Terris spent his early working life in radio and television. , Terris serves as the President of Media Matters in NZ, an advocacy group which campaigns against what it regards as gratuitous sex and violence in the electronic media. He published his autobiography Being Who You Are in 2004. In 2013 he published a handbook on How To Make a Speech and How To Run A Meeting. His latest book, released in July 2014 and called September Showdown is a light-hearted look at the perils of a parliamentary career. He has an interest in heritage issues and regularly contributes to the Radio New Zealand programme Sounds Historical. Terris has also produced a series of six video documentaries on local subjects called Village to City, as well as a series of six interviews with local Hutt people who lived through World War II, both of which he has donated to the Hutt City Libraries. He is a member of the Queen's Service Order and was awarded the New Zealand 1990 Commemoration Medal. He became a RotaryPaul Harris Fellow in 2005.