Media lawyer Paul Gilbert has told Daybreak that judges will have to decide on "whether or not a tweet itself is more than shocking or offensive."
He added: "It's finding a balance between what the law says about this and the freedom of speech."
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A grey start to the weekend with patchy rain for Scotland and eastern England.
A 31-year-old, stabbed nine times when he asked a man to stop harassing his girlfriend, has raised more than $28,000 for hospital treatment.
The Prince has called for "zero tolerance" on the ivory trade, which he says is increasing "alarmingly".