Why would Victoria Police arrest a teenager who's shared film of a friend? The latest stage in the St Kilda nude photos story raises the question of how much – and what – we can record of our life and the people in it.

Generally, if you're in public, you can film what you like, ignoring for the moment any local council restrictions and some of the lesser known parts of the Copyright Act concerning pictures of artworks and buildings. Once you move indoors, it gets more complicated.

The first place to start is Victoria's Surveillance Devices Act 1999. There are similar (but not identical) laws around the country.

Basically, in Victoria,

  • you can't film someone engaged in a private activity without his/her consent if you're not also engaged in the activity
  • even if you made the film with that person's consent, you can't communicate or publish it to anyone else without his or her consent.

If you do, you could be liable in Victoria to a fine of up to $28, 668 and up to two years in prison. The Surveillance Devices Act also specifically restricts the type of surveillance that an employer can install.

There are however some exceptions.

Most of them relate to law enforcement, but Victoria does also allow communication or publication if it's "no more than is reasonably necessary" in the public interest; or for the protection of the lawful interests of the person making it.

The $64,000 question is "what's a private activity?"

The Victorian Act defines private activity as "an activity carried on in circumstances that may reasonably be taken to indicate that the parties to it desire it to be observed only by themselves." The fact that the subject consented to the making of the video (if that is the case) does not mean it is not a private activity; on the other hand, the mere fact that the subject was in a state of some undress does not mean that it was a private activity either. If the case proceeds we may get some answers to these issues.

So the basic message in the meantime is: be careful with that camera!