A more thorough explanation:

communi consensu

When everyone agrees on something, it is said to be done communi consensu. This is a Latin phrase that means "by common consent."

• The decision to cancel the game was made communi consensu by the coaches and players.
• The committee reached a conclusion communi consensu after discussing all the options.

These examples show that when a group of people come to an agreement or make a decision together, it can be described as being done communi consensu.