If someone is in trouble with the law, they are being questioned by the police in connection with something illegal or criminal.
"The suspect has often been in trouble with the law."
kangaroo court
A kangaroo court is an illegal tribunal set up by a group of people who have taken the law into their own hands and conduct trials which deny fundamental justice.
"Calm down please! Is this a meeting or a kangaroo
Someone who is judge, jury and executioner has full power to judge and punish others unilaterally.
"OK. Report him to the authorities if you suspect him. You can't just appoint yourself judge, jury and executioner!"
justice is blind
This expression means that justice is impartial and objective. Everyone is equal before the law.
"There's no way he'll get preferential treatment. Justice is blind."
A situation in which people are prepared to use unscrupulous methods in order to succeed or survive is called the law of the jungle.
"Some businesses today seem to be governed by the law of the jungle."
If someone is a law unto themselves, they do things their own way and ignore what is generally considered as acceptable.
"They're against discipline and allow their children complete freedom - they're a law unto themselves."
Someone who lays down the law tells people very forcefully and firmly what they must do.
"The volunteers helped in a disorganised way. They needed someone to lay down the law."
