A claim other than a claim by the claimant against the defendant. It includes (1) a counterclaim by the defendant against the claimant; (2) a counterclaim by the defendant against a third party (i.e. a person who is not a party to the current proceedings), normally with the claimant; and (3) a claim by the defendant for an indemnity or a contribution from either a third party or from a party to the current proceedings. If the defendant to a claim alleges that a third party is liable to indemnify him or contribute to any judgment, or is someone that they seek to counterclaim against in addition to the claimant, he must bring that party into the proceedings by issuing a Part 20 claim form. Once done, the third party becomes known as the Part 20 defendant.
A defendant can issue a Part 20 claim form without requiring permission of the court if it is issued before or at the time of the filing of his defence. Directions in such a case will be dealt with as part of the normal system of case management appropriate to the track to which the case has been allocated. If the time in which the defence must be filed has expired, permission is required from the court. This is normally sought by the use of an application notice filed at court and supported by evidence of reasons why the third party be introduced into the proceedings. If granted, the court will issue directions at that time. In any event, the court will consider further directions as to the future conduct of the proceedings when the time for filing the defence to the Part 20 claim by the third party or co-defendant has expired.