When an agreement, contract or treaty is signed, sealed and delivered, all the legal documents are in order.
"It is hoped that the agreement will be signed, sealed and delivered before the end of the week"
smoking gun
A smoking gun is a piece of evidence or the indisputable sign of someone's guilt.
"The fingerprints left on the door-handle was the smoking gun that enabled the police to arrest him."
take the law into one's own hands
If, instead of calling the police, you personally take action against someone who has done something wrong, you take the law into your own hands.
"Instead of calling the police, he took the law into his own hands and confronted the youth who had stolen his son's scooter."
toe the line
If someone toes the line, they obey the rules and accept the principles laid down by a person, group or organisation.
"If you want to stay in this school, you'll have to learn to toe the line.
