The general scope of third-party procedure is to deal with cases arising out of transactions between the Plaintiff and Defendant and third party, to try and settle them in one action.
The law is that in order for a third party to be lawfully joined, the subject matter between the third party and the Defendant must be the same as the subject matter between the Plaintiff and the Defendant and the original cause of action must be the same.
The Defendant should have a direct right of indemnity/compensation, which right should have, arisen from a contract express or implied.
The right to indemnity/compensation exists where the relationship between the parties is such that in law and in equity, there is an obligation upon the one party to indemnify/compensate the other.
There are cases in which the state of circumstances is such that the law attaches legal or equitable duty to indemnify/compensate arising from a promise by a person to do that which under the circumstances he ought to do.
Where the Defendant is sued and he thinks another person is responsible, he may sue the 3rd party by bringing 3rd party proceedings.
The object of 3rd party proceedings is to prevent filing many suits in Court and the procedure is limited to a claim of indemnity/compensation and contribution over or against any person not a party to the suit. The Plaintiff may issue a notice to 3rd party with leave/permission of Court. This notice has to be served with the plaint on to the 3rd party.
Apart from the causes of action being the same, the right to indemnify/compensate the Defendant by the third party must have been provided by the original contract either impliedly or expressly.
The law provides for appearance of 3rd parties for directions. Where the 3rd party files a defence, the Defendant who gave 3rd party notice may apply to Court for directions as to questions on how the issues between him and the 3rd party are to be tried and the first question is whether there is a question for trial between the 3rd party and Defendant and the onus is on the Defendant to prove that there is a question of liability on the Defendant by the 3rd party [defendant admits that he is liable but it is the 3rd party to pay].