Roger Clinton DUI Arrest in Cali ... Impeccable Timing

6/6/2016 6:18 AM PDT

Roger Clinton -- DUI Arrest in California ... Impeccable Timing (UPDATE: MUG SHOT)

EXCLUSIVE

9:45 AM PT -- Clinton got sprung. He posted bail, and is scheduled to be in court in September.Hillary Clinton's brother-in-law is sitting in a jail cell after getting busted for DUI in Southern California ... just 2 days before the crucial CA primary vote. 

Law enforcement sources tell TMZ ... Roger Clinton was arrested Sunday just after 8 PM in Redondo Beach. He was booked for driving under the influence, and we're told he refused blood alcohol testing.

Roger remains in police custody. His bail is set at $15,000.

Clinton was also arrested for DUI in 2001. That same year, President Clinton infamously pardoned his half-brother for a drug charge. 

Unless he bails out before Tuesday ... there goes one vote for Hillary.