A briar patch is a thorny, tangled patch of vines. Generally they are "sticker vines" like blackberries, but they can also include any other vine or plant that has gotten mixed in with the tangle. These types of vines can be difficult to kill without also killing the desirable plants around or underneath them. However, with the proper combination of methods, you can get rid of briar patches without sacrificing the rest of your plants.
Protect yourself. Wear long pants, a long-sleeved shirt and garden gloves.
Cut the vines back to the roots. This will not kill them entirely in most cases, but it will slow their growth down because they will not have the benefit of their leaves. Remove all the plant debris from the area.
Plant the area with competitive plants. If you are trying to create a lawn out of brambles, for example, then seeding that area will help control your briar patch because the grass will compete with the briars.
Mow the area regularly. Keeping your briar vines short will eventually kill them. Do not mow any more often than your new grass can handle, however.
Target stubborn vines with vinegar. If you have some vines that just will not quit, then spot treat them with vinegar. Be sure to hit only the vine when you are spraying, since vinegar will also kill your grass.