Britney Spears’ first husband Jason Alexander is rushing to her defense after her DUI arrest … calling people out for jumping to conclusions when the full story isn’t even out yet.

In an IG Reel, Jason — who was famously married to the singer for just 55 hours before their annulment in 2004 — pointed out her reported 0.06 blood-alcohol level is actually below the legal BAC limit in most states. He also said it’s possible any substances in her system could’ve been legally prescribed medication, which would change the narrative entirely.

Jason doubled down, saying it’s unfair for the internet to run with “drunk driving” speculation before the facts are confirmed … adding rumors spread fast and people end up judged before the truth is even clear.

As we reported, Britney was arrested Wednesday night for allegedly driving under the influence in Ventura County, California. The pop star was taken to a hospital after the arrest before being transported to jail. She was released Thursday morning and is due back in court in May.