Getting convicted for a DUI can be career ending. The key term here, however, is convicted, because as most of us learned in grade school, a person charged with a crime is innocent until proven guilty. But, even a DUI arrest can have a negative impact on your job.
Generally, nearly all employment in the US is "at-will" employment. This means that an employer can fire an employee for pretty much any non-discriminatory, or non-retaliatory, reason. While it may seem unfair, generally, private employers will be able to fire an employee even for just being arrested. If your arrest receives publicity, such as being listed in a local newspaper's blotter, your employer may not be too pleased with that, especially if you have a public facing role in your company.
One of the more common reasons a DUI arrest will get someone fired is due to absences from work (or repeated tardiness). Employers usually require that employees provide some advance notice for taking time off. If you are arrested, you may not be able to provide any notice at all.
While you may be able to avoid jail time, if you have to miss work for court appearances, or community service, your employer probably has a policy that explains the consequences, which usually includes termination for repeat offenses. Frequently, after an arrest and/or conviction for DUI, because most states will suspend driving privileges, getting to work on time may be much more difficult. After an arrest or conviction, you may want to consult with an attorney on whether you should advise your employer or not.
Security Clearances and Codes of Conduct
In many jobs that require some level of security clearance, being convicted of a DUI can actually lead to termination. The rationale behind this is that an employee that is trusted with confidential information will appear to be less trustworthy if they have a conviction that shows a lapse in judgment.
Similarly, some employers require employees to adhere to a code of conduct both in and outside of work, and even on the internet. For public employers, there are limits to these, but not for private employers.
The most vulnerable group of employees are commercial drivers. If a person drives for a living, their employer is likely to fire them for merely being arrested for a DUI, especially if the job involves driving people around. Most states prohibit commercial drivers from maintaining their commercial driver's license if they are convicted of a DUI.