A more thorough explanation:

A nonintromittent clause is a legal term used in English law. It refers to a clause in the charter of a borough that exempts it from the jurisdiction of the justices of the peace appointed for the borough's county.

For example, let's say there is a borough called "Smithville" that is located in the county of "Jones." If Smithville has a nonintromittent clause in its charter, it means that the justices of the peace appointed for Jones county do not have jurisdiction over Smithville. This means that any legal matters that arise in Smithville would be handled by a different court or authority.

Nonintromittent clauses were often included in charters to give boroughs more autonomy and independence from the county in which they were located. This allowed them to govern themselves and make their own decisions without interference from outside authorities.