Students must have the 'consent' of their parents to go on the trip. = Students must have 'parental consent' to go on the trip.
This restaurant is, 'by common consent', the best in the city. [=people agree that this restaurant is the best in the city]
The contract was canceled last month 'by mutual consent'. [=the people involved agreed to cancel the contract]
(..) Ask me in an hour. I thought I'd try... ...one last time. You should have stayed in San Francisco, Dr. Kogan. By signing this consent form... ...you'd be donating your body to a noble cause. You'd... ...have a second chance, through my research, to live again. (..)2009 Terminator Salvation