Maybe it's happened to you: you're in public, maybe on the bus, in a café or the airport lounge and you suddenly realise the person next to you is watching porn. Sometimes not even with the sound off. What do you do? Or, more to the point, what can you do - is it against the law? And, actually, what is it safe to do?
These questions were raised last week on BBC Radio 4's Woman's Hour when Siobhann Tighe shared her experience of being on a bus home from work and realising the man next to her was watching porn. Her story sparked great debate, with many others sharing similar experiences.
So, first-things-first, is this against the law? Not surprisingly, there is no specific law covering watching porn in public. We're only having this debate now because smartphones, free wifi and cheap data are commonplace. Nonetheless, there are a few laws which the police could use if they were willing to take a case forward. First are the public order offences, though only if the porn-viewer was causing a real commotion, being threatening or harassing, or otherwise engaging in some form of abusive anti-social behaviour.
If not, then there is the common law offence of outraging public decency which requires a 'lewd, obscene or disgusting' act breaching contemporary standards of 'public decency'. Depending on the circumstances, this could be used in these circumstances, though it's a notoriously vague offence (though vital in some cases - such as 'upskirting').
There is also the Indecent Displays (Control) Act 1981 - originally designed to reduce advertising of sex shops. Potentially, watching porn in public could be a 'display' of 'indecent material' under the Act. But, prosecutions are extremely rare and the threshold of obscenity/indecency relatively high. Technically possible; doubtful in practice.
In the end, therefore, while porn-viewers in public might find themselves on the wrong side of the law, in reality prosecutions are extremely unlikely. Getting the police to take action, convince the Crown Prosecution Service to prosecute, and then to secure a conviction is going to be a challenge. Also, this requires you and I, as the affected members of the public, to challenge the person viewing the porn, report it to relevant authorities and be willing to pursue the case. Many of us, when faced with porn in public will just want to move, for it to end and will understandably fear for our safety if we challenge the person.
But just because the criminal law has little role does not mean viewing porn in public is ok. It's yet another commonplace form of street harassment, of sexual harassment, like having to put up with wolf-whistling. People viewing porn in public know they are making others uncomfortable, or worse. And they are comfortable with this; worse, this is part of the kick they are getting from watching porn in public. As Lauren Rosewarne says, 'choice is compromised when pornography consumption is taken out of the privacy of one's home and experienced in public space'. Being subjected to porn in public (and sometimes it is not possible to avert your eyes, avoid the screen, or the noise) is being subjected to non-consensual sexual activity. While each of us does have rights to read, or watch what we like in public on our own devices, there are limits and those freedoms end when the actions impinge on the freedom of others. While the porn-viewer is entitled to privacy and freedom, as members of the public, we too are entitled to privacy in public, and to feel safe (and experiencing porn in public can feel threatening).
Ultimately, this is an issue about culture and attitudes - and therefore why this public discussion is vital. We are all grappling with the dilemmas of the smartphone age - from the explosion of image-based sexual abuse including upskirting and sharing intimate images without consent, to this debate on watching porn in public. A new sexual ethics is being fashioned and this gives us the opportunity now to shape attitudes, ensuring that consent and respect shape our public and sexual lives.
Clare McGlynn is a Professor of Law at Durham University and an expert on the regulation of pornography