In the United States it is illegal to drive while under the influence of alcohol. This violation of the law is regulated by DUI laws. These laws are based off of a BAC or a blood alcohol concentration. Nationally, the blood alcohol concentration is measured in a percentage of 0.08. Based off of DUI law, anyone operating a vehicle above the legal limit is in violation of this law and subject to jail time, license revocation, and much more. Each individual state is allowed to have their own DUI laws and regulations that are the same or different than the national level. Whatever state a person is found violating DUI laws, they are subject to the states specific penalties regardless of residency within that state. The BAC test is a chemical one that tests either blood, urine, or breathe to determine whether someone is over the limit.
Additionally, each state in the United States has a Implied Consent law, which states that those with a drivers license have agreed to submit to taking a chemical test when asked properly by a police officer. DUI law in some states permits a guilty judgment to be made in an event that a driver refuses to submit to a chemical test. A driver basically proves in that moment that a police officer was accurate in his/her assumption that they were driving under the influence.
Some states are more lenient that others in regards to DUI law, however it is usually on the first offense only. In general, states require drivers to attend an alcohol Oasis class, which is used to evaluate a driver and see whether or not they have an alcohol abuse problem. In almost all cases DUI laws require a person to be taken to jail, and pay some fines. Sometimes states will require that a person get a wheel interlock system put into their vehicle. This device is has been increasingly adopted in more states to prevent drunk driving.
What it does is lock the drivers wheel until they blow into the device and assure that they are under the legal limit. After this is done the car will then and only then be able to start. This added penalty to DUI law has saved lives and made it easier on the court system to regulate it as well. In many states this device is used in a second offense or worse, however in some stricter states it can be used first. The wheel interlock device has created controversy with some that believe it imposes on a persons rights. The flip side to this is that once a person breaks the law, they are subject to losing their rights and privileges anyway. This device is a great way that someone can avoid jail.
Drinking and driving is extremely dangerous and can cause death among the drunk driver and others. DUI laws are respected because every year the majority of motor vehicle deaths are related to drunk driving. The purpose of DUI law is to regulate the dangerous behavior of individuals who are under the influence, and save lives.