A more thorough explanation:

Definition: Pluris petitio is a Latin term that means "overclaim" or "claiming too much." In Roman law, it refers to a claim for more than what is due, especially when a person claims more in their pleadings than what is actually owed.

For example, if a person sues someone for $10,000 when they are only owed $5,000, this would be considered a pluris petitio. This mistake of overclaiming was fatal to the action under classical law. However, under cognitio extraordinaria, a claimant could continue the action but could be liable for treble damages to any person injured by the overstated claim.

It's important to note that a plaintiff may overclaim in different ways, such as in substance, time, place, or cause. For instance, a plaintiff may claim a bigger amount than what is due to them, claim before the payment is due, claim at a place other than where the payment had to be performed, or claim a certain thing although the debtor had the right to choose between two or more things.

After the abolition of the formula-regime, the pluspetitio lost its actuality. Imperial legislation modified the severe provisions against overclaims. In Justinian's law, the plaintiff lost the case only if they maliciously persisted during the whole trial in their overclaim.