The decision handed the victory to Country House, which started the race at 65-1, and a first-time win to hall of fame trainer Bill Mott. That left two byproducts of note.
Officials cited Maximum Security for interference and the colt became the first Kentucky Derby victor to be disqualified for violating a state regulation that penalizes horses for impeding the path of another in a race.
Maximum Security was placed 17th (instead of last in the 19-horse field) because it put him behind all the horses affected by the incident.
It was a stunning victory and upset by long shot Country House.
"It feels pretty darn good".
No horse had ever been disqualified immediately after winning the United States' biggest race - though Dancer's Image was stripped of the title in 1968 after a post-race test showed traces of a banned substance. He appeared to win by 13/4 lengths in 2:03.93.
The running of the 145-th Kentucky Derby was full of excitement and controversy.
"I'm kind of speechless right now", Prat said, letting out a long sigh.
The stewards began reviewing video for the first such claim since 2001, when Monarchos's win over Invisible Ink stood after an objection.
Lawson says in most countries, Maximum Security's victory would likely have been upheld because officials have more discretion to determine where each horse would have finished had the interference not occurred.
Maximum Security was first named the winner, but minutes later, an inquiry ruling named Country House as the official victor. Jockey Luis Saez pulled the horse back into position and finished the race in the lead. Maximum Security was accused of blocking the path of other horses at Churchill Downs by making a wide turn on the rain-soaked track, contrary to the rules. I'm thrilled with the horse. Even if Country House defies the odds and wins again, this race will go down in history as Objection-gate.
Of course, when one door closes, another opens in gambling, and it paid off handsomely for anyone who bet on the 65-1 underdog Country House.
"As far as the winning goes, it's actually very ... it's bittersweet", Mott said. "I've been on the other end of it, just not in the Kentucky Derby".