WIRED:We are reaching a point where we really are carrying our livelihoods around with us in our pockets, writes DANNY OBRIEN

IT’S HALLOWE’EN, and a private party in one of the warehouses that scatter San Francisco’s South of Market district – traditional home of the city’s club scene and internet start-up community – is busted by the police.

Due to a somewhat bizarre city regulation, after-hours parties in San Francisco with live DJs need a special permit, and law enforcement has been cracking down recently.

But in what appears to be a change in policy by the city law enforcement, revellers at this party found that the police not only shut down their party, but seized the laptops guests were carrying as evidence.

Justin Miller, who had been using her computer to play CDs at one of the events, started crying when an underground police officer took her computer. “This is my livelihood,” she kept repeating.

It may seem strange to take a laptop to a party. But in San Francisco, where it’s not unusual to see every table in a cafe holding one or more computers, and a handful of commuters in every underground car park clutching a laptop bag to their chest, it is not uncommon.

The story of Miller, and others who have found themselves computerless as a result of the city’s “war on fun”, has provoked outrage in the local tech community, many of whom all too easily see themselves losing their livelihood as a result of a lost laptop.

Miller finally got her laptop back, nearly a month later, after a legal intervention by the local civil liberties organisation I work for, the Electronic Frontier Foundation. However, the questions that the seizure raises are still unanswered, and have ramifications wider than the San Francisco city limits.

First, what kind of evidence does a laptop provide anyway?

The police who seized the computers said they needed them to show that there was live DJing at the party. But they already had their own eyewitness evidence, and it’s not clear what factual information the existence of a laptop could give.

If having a laptop with you indicates anything at all it’s that you could be doing an incredibly wide range of tasks – most legal, but some not. Seizing it as evidence makes as much sense as seizing a car as evidence that you were capable of reaching the scene of a crime. It smacks less of gathering evidence and more of intimidating someone by removing a vital part of everyday life.

We’re reaching a point now where we really are carrying our livelihoods around with us in our pockets. Even if you’re not the laptop-lugger type, the chances are that the loss of a mobile phone could seriously impact on your job or your life, especially if it’s held in limbo for months. Many insurance policies won’t pay out if a computer is seized by the police – and if many of us are uncomfortable with the idea of a thief walking off with our mobile or laptop to reformat and resell, the idea of an increasingly tech-savy police force probing at a PC or smartphone web history, fishing for evidence, is even worse.

The social aspect of our digital companions adds to the toxic nature of these raids. Despite what live music lovers may demand, it’s not actually a crime to DJ or be a guest at even an “illegal” party. But, because computers can potentially be used to perform or share music, their possession gets caught up in the acts of others. And we collect information on others on our personal computers too. If laptops or mobile phones are seized by the police, they don’t just potentially reveal private data about ourselves – they can also be used as informants on our friends and colleagues.

A cache of my Facebook discussions, a list of friends I called or texted before I visited this party, past e-mails, passwords to private but shared sites: I carry all of these around with me, and suspect you do too.

There are two solutions to this change in the balance between police and private citizen. The first is in all our hands (literally). We can encrypt and password protect our laptops and our phones. Locking down laptops is relatively easy; unfortunately even smartphones don’t necessarily hide data in a way that snooping thieves or detective inspectors can’t unlock. Hopefully, as phones grow more powerful, companies like Apple will bring the same privacy-protecting features from their desktop range on to their mobile devices.

The other solution is to spell out – and enforce – what police can and can’t do with these powerful and expensive but portable pieces of equipment.

Even if the police in San Francisco get a rap on the knuckles for their over-enthusiastic raids, the problem of the police being able to find out more from our devices than we’d ever tell them will remain.

If we want to keep the same level of privacy from prying officers as we have had before now we need to tighten up the enforcement of what law enforcement can look at, and what we keep around for them to see.

San Francisco’s cops may be cracking down on private parties: but until I’m proven guilty, I’d like to remain one.