Over the past few days, a "free speech moment" has been unfolding. These are the controversies where we get to discuss the first principles of free expression, and they usually begin when someone does something extremely offensive. Think of the public trolling of Anjem Choudry, or the English Defence League.  Think of Liam Stacey, charged with a criminal offence for tweeting. Think of every controversial columnist, paid by the newspapers to be politically incorrect. These moments are frustrating, but at least campaigners like me are asked to make the case for free expression afresh, on sites such as this one.

This week, the "free speech moment" has had both an historical and international flavour. Günter Grass, the Nobel Prize Winning German author, angered the Israeli government after he wrote a poem about their militarism.  Israel, incensed that a former conscript in the Waffen-SS should write such a criticism, responded by placing a travel ban on the author.  In the most recent twist, Grass has escalated the controversy by likening the Israeli government’s actions to those of the East German Stasi.

There are two unresolved issues here.  The first is whether a travel ban (declaring Grass a persona non grata, unwelcome should he wish to visit Israel again) is censorship.  Clearly, such a move is less severe than the formal banning of Grass’s books; and many authors around the world (for example, in Iran, which was cited in the poem) suffer imprisonment for their transgressions. Nevertheless, placing this restriction on a person, purely because of what they have written, is a form of censorship.

It prevents any Israeli citizens who happen to agree with Grass’s poem (and I am sure there are many, from every religion) from inviting him to speak. It precludes the possibility that those in Israel who enjoy Günter Grass’s oeuvre would ever have the chance to meet him at a literary event.  A voice is suppressed. Until recently, the UK Border Agency were in the habit of denying authors and artists entry to the UK because a gallery opening or a book tour was considered a form of "work". English PEN campaigned for reform of the system [2] on the basis that freedom of expression also includes freedom of information, the right to hear dissenting voices. A travel restriction on an author denies this freedom, which makes it undemocratic.

Such bans also have a "chilling effect" on other writers – will authors who regularly visit Israel now self-censor, if they hold opinions that the Israeli government doesn’t want to hear?

The second issue is over Günter Grass’s actual words, including his latest ‘Stasi’ interjection? These "free speech moments" are frustrating because defending someone’s right to say something is usually equated with defending the content of what they say. Those whom the speaker has offended are always ready to conflate the two issues. We should remember that the oft-cited Tallenter quip on free speech (“I hate what you say, but defend to the death your right to say it”) also works perfectly well in reverse: I defend Günter Grass’s right to say things . . . but I hate what he says. The writer Kenan Malik goes further, and makes the point [3] that if one vigorously defends free expression, one also has a moral duty to retort when people say unpleasant things.

I don’t think that Günter Grass is saying abhorrent things, though in my opinion he has been deeply insensitive. His last comment is clearly a doubling-down, and the result is polarising. His poem, despite taking on the form of introspection, has not persuaded anyone that was not already of his point-of-view. For such an accomplished writer, celebrated for his turn of phrase, this is a shame. The great power of poetry and prose is their ability to help the reader empathise with someone of a different culture or history. Personally, I think Grass is capable of this, and should have written a different poem.  But to say this is an act of literary criticism, not a statement of the principles of free speech.

Robert Sharp is head of campaigns & communications at English PEN