Very serious? Millions of people in the US have one with no serious effects on them whatsoever (I'm talking of DIU and being caught, not hitting someone on it). E.g.:
"The penalties for drunk driving vary among states and jurisdictions. It is not uncommon for the penalties to be different from county to county within any given state depending on the practices of the individual jurisdiction. Some jurisdictions require jail time and larger fines, even on a first offense. For instance, Ohio requires a mandatory 72-hour jail sentence for a first offense conviction; however, the jail time component is satisfied by attendance of the Ohio A.W.A.R.E. Program, which is a 72-hour alcohol-education program. Compared to many other countries, such as Sweden, penalties for drunk driving in the United States are considered less severe unless alcohol is involved in an incident causing injury or death of another, such DUI, DWI or OWI with Great Bodily Injury (GBI) or Vehicular Manslaughter."
"Wisconsin regards first offense drunk driving as a municipal offense, and New Jersey treats all drunk driving cases without serious injury or death as traffic violations."
You're talking about people already in the US (citizens/residents). If you're trying to get a US visa from your country and you have a DUI on your record, it makes it much more difficult to get approved.
FYI, a US citizen with a DUI will likely get denied entry into Canada -- you usually need to be deemed "rehabilitated" or be granted a temporary stay visa before allowed in.
This not only costs thousands of dollars – a very significant amount of money to the vast majority of Americans – but it also SEVERELY limits an individual’s ability to drive a work vehicle.
Yes, prison time is not always involved, but the financial cost of a DUI can be quite serious.
"The penalties for drunk driving vary among states and jurisdictions. It is not uncommon for the penalties to be different from county to county within any given state depending on the practices of the individual jurisdiction. Some jurisdictions require jail time and larger fines, even on a first offense. For instance, Ohio requires a mandatory 72-hour jail sentence for a first offense conviction; however, the jail time component is satisfied by attendance of the Ohio A.W.A.R.E. Program, which is a 72-hour alcohol-education program. Compared to many other countries, such as Sweden, penalties for drunk driving in the United States are considered less severe unless alcohol is involved in an incident causing injury or death of another, such DUI, DWI or OWI with Great Bodily Injury (GBI) or Vehicular Manslaughter."
"Wisconsin regards first offense drunk driving as a municipal offense, and New Jersey treats all drunk driving cases without serious injury or death as traffic violations."