X. Every cause in which one side attacks and the other defends consists either of one or more controversial questions. In the first case it is called simple, in the second complex. An example of the first is when the subject of enquiry is a theft or an adultery taken by itself. In complex cases the several questions may all be of the same kind, as in cases of extortion, or of different kinds, as when a man is accused at one and the same time of homicide and sacrilege. Such cases no longer arise in the public courts, since the praetor allots the different charges to different courts in accordance with a definite rule; but they still are of frequent occurrence in the Imperial or Senatorial courts, and were frequent in the days when they came up for trial before the people. In the permanent courts ( quaestiones perpetuae ). There were separate courts for, different offences. In cases brought before the Senate or the Emperor a number of different charges might be dealt with at once. Private suits again are often tried by one judge, who may have to determine many different points of law.

There are no other species of forensic causes, not even when one person brings the same suit on the same grounds against two different persons, or two persons bring the same suit against one, or several against several, as occasionally occurs in lawsuits about inheritances. Because although a number of parties may be involved, there is still only one suit, unless indeed the different circumstances of the various parties alter the questions at issue.

There is however said to be a third and different class, the comparative. Questions of comparison frequently require to be handled in portions of a cause, as for instance in the centum viral court, A civil court specially concerned with questions of inheritance. when after other questions have been raised the question is discussed as to which of two claimants is the more deserving of an inheritance. It is rare however for a case to be brought into court on such grounds alone, as in divinations Divinatio is a trial to decide between the claims of two persons to appear as accuser, there being no public prosecutor at Rome. cp. Cicero's Divinatio in Caecilium. which take place to determine who the accuser shall be, and occasionally when two informers dispute as to which has earned the reward.

Some again have added a fourth class, namely mutual accusation, which they call ἀντικατηγορία Others, however, regard it as belonging to the comparative group, to which indeed the common case of reciprocal suits on different grounds bears a strong resemblance. If this latter case should also be called ἀντικατηγορία (for it has no special name of its own), we must divide mutual accusation into two classes, in one of which the parties bring the same charge against each other, while in the other they bring different charges. The same division will also apply to claims.

As soon as we are clear as to the kind of cause on which we are engaged, we must then consider whether the act that forms the basis of the charge is denied or defended, or given another name or excepted from that class of action. Thus we determine the basis of each case.