The more documentaries I watch, the more cynical I get. If you look deep enough, you can always – always – see someone with a barrow to push. Years ago when I interviewed Canadian filmmaker Mark Achbar about The Corporation, he said quite bluntly that 'objectivity is a myth'.

There was a movie some time in the last few years called Unacknowledged, all about the long term US government cover-up about UFOs and contact with aliens. It was only when you scratch the surface the tiniest amount (it didn't seem they were trying to hide it) that the main talking head was the executive director of a project trying to get the truth about the US government's knowledge about extraterrestrial life declassified.

And it was while watching this movie about political correctness gone mad in the face of stand-up comedy that I saw the slightly sinister influence of right wing politics, a lot like those supposed community groups tarring themselves with the brushes of freedom and liberty when they were secretly set up and run by tobacco and firearms manufacturers.

Conservatives are always the first ones to jump up and down about free speech in the face of cancel culture, and what better way to get that agenda in front of people – especially cinemagoing liberals – than to make a hip documentary about it?

Of course, I might be reading too much into it. On the surface, it's the story about how hot button issues that were previously a comedian's bread and butter are now decidedly off the table and will result in everything from cancelled gigs to death threats if you go there.

The assembled comics and academics include Penn Jilette, Lisa Lampanelli, Jim Norton and many more. Gilbert Gottfried has never apologised for going too far and was a recent victim of the kind of thing the movie's talking about – after pretty tasteless jokes following the 2011 Japan earthquake he was dropped by the insurance company he was doing advertising work for.

But they all wax lyrical about the days when you could slur a group or event and the audience were adult enough to realise it's in humour. Refrains from 'if it offends you don't watch it' to 'it's a joke, we don't really think that' are implicit in almost all the opinions and proceedings presented.

Most surprising however – and I'll admit the producers could have cherry picked evidence to back this up – is how the staunchest opposition to edgy humour is found on college campuses across America, the kind of places you'd expect ribald, religious or political comedy to catch on.

Director Ted Balaker seems to believe all roads lead back to Lenny Bruce. He's very revered among those interviewed for the material he used and the punishment he suffered for it (from the law – not audiences) and the story of his acts, arrests and death gets a large amount of screen time.

It seems to have its heart on its sleeve – especially as you look at Balaker's past catalogue and see that it isn't the first time he's made movies about free speech – and we'll probably never know whether shadowy special interests had any hand in it. But it's not likely to change your opinion of cutting edge comedy and at-times tasteless jokes. Besides, Gottfried's joke about how he loves free speech because he's Jewish and doesn't want to pay for speech makes anything in the movie that rubs you the wrong way worth it.