Bobby Brown -- Freed In Record Speed

UPDATE: Even though Bobby's been sprung from the pokey, he's still not entirely free. He's under house arrest and has to wear an electronic monitoring bracelet for a grand total of 8 days. Nice gig.

It's a testament to how incredibly screwed up our justice system is ... Bobby Brown -- who was sentenced to 55 days in jail for his 3rd DUI -- just served a grand total of 9 HOURS in jail ... TMZ has learned.

Brown checked into L.A. County Jail at 9:58 AM Wednesday. He was released at 6:58 PM. Interesting ... an L.A. County Sheriff's spokesperson said just days ago Brown would serve 9 days ... but the jails are bursting at the seams and this is what happens ... kind of a joke, don't you think?

Brown was arrested in October after driving erratically on an L.A. street. He pled no contest to DUI and driving on a suspended license. It was his second DUI arrest in 7 months.

Bobby is on 4 years probation and has to attend alcohol ed classes for 18 months.