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.
2. legislation-the act of making or enacting laws. lawmaking, legislating. governing, government activity, government, governance, administration-the act of governing; exercising authority; regulations for the governing of state prisons; he had considerable experience of government.