The new Banksy shows a judge beating a defenceless protester. (Banksy)A new artwork by Banksy outside the Royal Courts of Justice in London has been covered up within hours of its appearance.The mural, spotted on Monday, depicts a judge in a wig and a gown beating up an unarmed protester with a gavel.The piece of art, below a CCTV camera on an external wall of the Queen's Building, part of the Royal Courts of Justice complex, has been concealed by large sheets of black plastic and two metal barriers, and is being guarded by security officials.