A more thorough explanation:

Definition: Ex mero motu is a Latin phrase that means "on his mere motion." It refers to doing something voluntarily, without any suggestion or influence from another person. In the past, it was sometimes used in reference to a court, as an equivalent of "sua sponte" or "on its own motion."

Example: The judge dismissed the case ex mero motu, meaning that he did it on his own without any prompting from the parties involved.

Explanation: The example illustrates the definition of ex mero motu because the judge made the decision to dismiss the case voluntarily, without any suggestion or influence from the parties involved. He did it on his own, based on his own judgment and without being prompted by anyone else.