Plea bargain

"I accidentally 93MB of Sarah Palin rar files."

Not a get-out-of jail card

My very lucrative sideline is as an expert witness in computers and communications. I work mostly in criminal cases.

The first point is that almost all computer systems used by consumers of child porn have malware - usually more than one type. This is because their cruising habits expose them to some pretty dodgy sites. The same applies to pedophiles who try and groom under-age kids. Drug dealers and general crooks tend to be less exposed.

The second point is that the technical evidence and presence of malware almost never has a bearing on the outcome. Juries are very eager to discount the presence of malware and instead rely on the human factors. Usually the video of the initial search and the half-assed excuses and minor admissions during interview are enough to convict.

Another common excuse is that 'someone else used my computer'. This is difficult to prove either way. However juries generally think "this was his computer so he must have done it."

You need very powerful evidence that malware was actively being used. For instance an intercept at the ISP showing someone in Russia controlling the machine. Since the defendant won't have this record and the authorities don't routinely collect evidence that may exonerate the accused, this almost never occurs.

What is more interesting is unprotected wireless access points. If the access point is unprotected and all that is discovered is use of the IP connected to the access point then any good lawyer can get a not guilty verdict.