Early in Dean's political career, she served on the Waitaki District Council, representing the Oamaru ward.

Dean subsequently raised the matter in 2021 with Collins as part of the Francis review of Parliament's workplace culture.

[11][12] In May 2022, Dean confirmed that she would not be contesting the 2023 New Zealand general election and would retired at the end of the 2020–2023 parliamentary term.

[14] In 2007, Dean campaigned for the banning of the sale of "party pills", namely benzylpiperazine (BZP), over which Associate Health Minister Jim Anderton (leader of the Progressive Party) accused her of indulging in political grandstanding, saying, "Perhaps Mrs Dean doesn't subscribe to the idea that any Government must balance the need to act promptly with its responsibilities to act fairly and follow due process, particularly where its actions affect those who are currently acting within existing legal constraints.

[19] In November 2007 Dean called for the government to take action against Salvia divinorum, saying, "Salvia divinorum is a hallucinogenic drug, which has been banned in Australia, and yet here in New Zealand it continues to be sold freely" and "We’re dealing with a dangerous drug here, with the minister's wait and see approach like playing Russian Roulette with young people's lives.

"[20] In March 2008 she was reportedly pleased on hearing about plans for action against salvia but saying she was not hopeful it would be fast, given that it had taken the Government two-and-a-half years to move on BZP.

[21] Opponents of prohibitive Salvia restrictions argue that such reactions are largely due to an inherent prejudice and a particular cultural bias rather than any actual balance of evidence, pointing out inconsistencies in attitudes toward other more toxic and addictive drugs such as alcohol and nicotine.

[28] In August 2007, as a result of emails from ACT on Campus members based loosely around the well-known dihydrogen monoxide hoax, she sent a letter to Associate Health Minister Jim Anderton, asking if there were any plans to ban "dihydrogen monoxide", apparently not realising that it is the chemical name of water.

STANZ Chairman Matt Bowden said, "The DHMO hoax played on the member this week is not a joke, it highlights a serious issue at the heart of drug policymaking.