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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It will be a misty and cloudy start in many southern and central parts which will slowly lift this morning.
The president-elect also warned US companies they would face "retribution" for setting up their business operations abroad.
Penalties of £100 or a court fine of up to £1,000 can now be handed to anyone caught lighting up in a private vehicle with someone under 18.