When you drink alcohol, it passes directly from your stomach to the bloodstream. Your blood alcohol level, or BAL (B-A-L), is measured in milligrams of alcohol per 100 milliliters of blood, or in milligrams percent. A BAL of .10 (point one oh) means you have one percent of alcohol in your blood. Because the liver can only handle a certain amount of alcohol at a time, usually about one drink per hour, the remainder accumulates in your bloodstream and impairs many normal functions such as the ability to coordinate movements, exercise good judgment, and perform basic motor functions. For this reason, driving under the influence of alcohol is extremely dangerous. In most states, the permitted BAL while driving is .08 (point oh eight) or .10 (point one oh). A man weighing 180 pounds who consumes four beers in a two-hour period can expect his BAL to be well over the legal driving limit. Police sometimes use breath-analyzing machines to estimate BAL, although tests performed on blood or urine samples are generally regarded as being more accurate. Many states have regulations obliging you to provide a breath, blood, or urine sample, if requested.