Joint and several liability
Joint and several liability is a broad form of contractual liability which combines the separate doctrines of joint liability and several liability. It arises where two or more persons party to the same contract jointly promise to do something together, and severally make separate promises to do that same thing as well. This type of contractual arrangement gives rise to one joint obligation and as many several obligations as there are promisors. The other party therefore has discretion to sue all the parties together, or each separately. This is because until the obligation is discharged, each individual involved is liable for the entire obligation. Performance by one person will discharge all the others.
Where a party has paid more than their share of a debt or obligation, they may seek to recover the excess from the other parties in equal shares in absence of an agreement to the contrary.