Records from courts and tribunals across Australia show that, for some people, December is a time not only to drink to excess but to abuse, assault or sexually harass colleagues, or to give them inappropriate gifts.

In the worst cases, employers have paid hundreds of thousands of dollars in compensation and individuals have copped criminal charges.

A senior associate at legal firm Bradley Allen Love, Jennifer Wyborn, says that, even when a work-organised party is after-hours and no one is "working", the event is, effectively, an extension of the office.

"Put simply, the Christmas party is a 'workplace', regardless of when and where it's held."

Under workplace safety laws, employers could also be liable for any harm that befell volunteers who helped out at the event, she said.

At last year's Christmas do for Airservices Australia's Melbourne staff, a senior male manager allegedly groped and bit a junior female colleague.

An earlier, higher-profile dispute involved a Telstra shopworker who stripped and had sex with two male co-workers in a hotel, in front of appalled female colleagues.

After two appeals, Telstra won the right to sack her, arguing that, although her misbehaviour took place after the Christmas function, it was still "at work".

This year, the Federal Court ruled that a trucking business owner sexually harassed his younger receptionist when he gave her, as a Christmas gift, "lingerie and a pair of purple fluffy handcuffs", even though the pair had previously had an intermittent sexual relationship.

Ms Wyborn said it was best to avoid "joke" presents that might be taken the wrong way.

And her advice on sex with colleagues?

"Just don't do it! It may be that, in many cases, this has occurred and the couple ended up married and in a wonderful relationship," she said.

"The difficulty is when it goes rotten and one party doesn't accept that it's ended.

"In the private sphere, this may be seen as a desperate or clingy ex-partner, but it can become sexual harassment if it's in a workplace."

Perhaps the simplest way to avoid trouble while merrymaking, however, was to enjoy an alcohol-free Christmas party, she said.

"Or at least be very careful about the amount."