Free speech and its ramifications are at the heart of "Shut Up & Sing," which recognizes that for the celebrity, engaging in a public exchange of ideas and opinions isn't always without its costs. The price can be dire.

The movie isn't quite the idolatrous you-go-girl portrait one might expect.

Shut up & Sings shows that it is all about freedom of speech and expression and how we had better not forget it. Freedom of speech, speaking out and having a voice. Yeah! On to the Grammies Dixie Chicks. You go girls!

It isn't a disciplined doco, and the fragmentation of the throughline makes for occasional sags in the film, but the filmmakers mean well.

They do make a comeback of course – almost stronger than ever – in this, the best documentary of the year so far. ­Intelligent, honest, heartfelt and fascinating.

I came round to them by the end, but it's not a great introduction.

This a frank, and slightly scary film about one of America's most cherished democratic privileges - freedom of speech - and how you're more than welcome to it as long as you don't say anything controversial. Then you're off the air.

A gold statue of the Dixie Chicks should be erected in Maines' hometown of Lubbock, Texas.

It was a throwaway scrap of a comment tossed to an audience baying with appreciation.