Why do some people go to jail when they get their first DUI and some people don’t?

This depends on a number of factors. Technically the charge carries a max of 12 months in jail. Which means it is up to the jurisdiction and judge. Each jurisdiction has it’s own policies. For example; a DUI first offense in Chesterfield County, would normally not require any active jail time, however a DUI in Richmond will typically land you in jail for one day. There are also mandatory minimums for blood alcohol levels that are over a certain point. Anything over .15 will get you a mandatory 5 days in jail. Also, there are increased penalties for other instances like, having children in the car at the time. Just because your friend or someone you heard of didn’t go to jail for a first offense DUI, doesn’t mean you won’t. Hire an attorney!