In State Bank of India Vs. Ranjan Chemicals Ltd. and Another, , the Supreme Court indicated the circumstances wherein a joint trial could be ordered:
A joint trial can be ordered by the court if it appears to it that some common question of law or fact arises in both proceedings or that the right to relief claimed in them are in respect of or arise out of the same transaction or series of transactions or that for some other reason it is desirable to make an order for joint trial. Where the plaintiff in one action is the same person as the defendant in another action, if one action can be ordered to stand as a counterclaim in the consolidated action, a joint trial can be ordered. An order for joint trial is considered to be useful in that, it will save the expenses of two attendances by the counsel and witnesses and the trial Judge will be enabled to try the two actions at the same time and take common evidence in respect of both the claims. If therefore the claim made by the Company can be tried as a counterclaim by the Debt Recovery Tribunal, the court can order joint trial on the basis of the above considerations. It does not appear to be necessary that all the questions or issues that arise should be common to both actions before a joint trial can be ordered. It will be sufficient if some of the issues are common and some of the evidence to be let in is also common, especially when the two actions arise out of the same transaction or series of transactions.
A joint trial is ordered when a court finds that the ordering of such a trial, would avoid separate overlapping evidence being taken in the two causes put in suit and it will be more convenient to try them together in the interests of the parties and in the interests of an effective trial of the causes. This power inheres in the court as an inherent power.