serious offence BrE
serious offense AmE

Destruction of libraries today is just as serious an offence.

But even to wander a few yards from the road was a serious offence.

This is a serious offence and the message must go out that people cannot take photos.

Taking a photograph in a court can be seen as a serious offence, leading to a prison sentence.

The first serious offence to be tried without a jury for 350 years was allowed to go ahead in 2009.

In addition to all else it is, of course, a serious offence.

That's a serious offence and Dennis is going to have to take some kind of action.

For less serious offences, the penalty is a fine of up to £2,500.

The Americans also want to cover other serious domestic criminal offences.

Trials for serious offences must usually be held before a jury.