Why do lawyers and judges in court wear that white hood on their heads?

This is only true in common law countries, and it is also true in Hong Kong movies. Wearing a white wig is a tradition, which embodies the justice of the law and shows that judges will try cases fairly without external influence.

As for that word, the judge didn't say it, but the clerk shouted it. The judge said it when he entered the court. It should be "call", which means to let all people stand up to show respect for the judge and indicate the beginning of the court trial.