For example, Brash plays fast and loose with our history.
We all know what happened to Māori during the 19th century, but Brash only looks at 1840, insisting that Māori ceded their sovereignty and then effectively disappeared, certainly as a group with an autonomous political interest.
Of the intervening 150 years or so, described by historian Claudia Orange as "years of turbulence", Brash is silent.
Then there is the problem of language. Brash and supporters talk about "Māori separatism", "Māori privilege", "Māori favourtism", "special deals for Māori", with words added for effect like "race-based", "apartheid", "part-Māori", "skin-colour" and even "Nazi Germany".
Such words and phrases are carefully coded, and are difficult to counter in any rational debate because of the emotional weight they carry. They frighten more than they inform.
They bring to mind the fear of Māori felt by colonial pākehā, which - according to historian Alan Ward - accounts for so much of our troubled past.
Such language also demonises Māori today who, further, are said to be trying to impose a "Māori cultural framework on our day to day existence, ignoring our British culture and traditions".
Freedom of speech gives Don Brash the platform he needs to employ his disingenuous language, adding weight to a troubling amalgam of deep-seated views, all the while showing a reckless disregard for the complexities of our shared histories.
In this context, freedom of speech is really about freedom of rhetoric - it's about sound over substance, it's about acrimony over accommodation.
It's also a double-edged sword. In the hands of the wrong people, it can do enormous damage.
Danny Keernan lives in Whanganui and has a PhD in Maori history. His research area of interest is Maori political history of the 19th century.
