Basically the issue with the knees is you don't want to start riding a horse too strenuously until the knees close. For each breed it is different. Some close at 3, others, like drafts and WBs, can wait until 5 or so.
the act of making or enacting laws. 2. a law or a body of laws enacted. Origin of legislation.
A statute is a written law passed by a legislature on the state or federal level. Statutes set forth general propositions of law that courts apply to specific situations. A statute may forbid a certain act, direct a certain act, make a declaration, or set forth governmental mechanisms to aid society.