Justify's ancestors include Secretariat, Count Fleet, War Admiral, Omaha, and Gallant Fox, all of whom also won the American Triple Crown.

On September 11, 2019, it was revealed via The New York Times that Justify tested positive for scopolamine, a banned substance that can be performance enhancing, in excess of what is normally found in tainted feed.

[12] Justify was sold at the 2016 Keeneland September Yearling Sales for $500,000 to a recently formed partnership between WinStar Farm (60% ownership), China Horse Club (25%) and SF Racing (15%), the latter run by employees of George Soros's investment firm.

[19] Justify did not make his first start until February 18, 2018, in a maiden special weight race for three-year-olds at Santa Anita Park over seven furlongs.

The impressive win earned a Beyer Speed Figure of 104 and caused the Thoroughbred Daily News to designate the colt as a "Rising Star".

As the overwhelming 1-20 favorite, he broke slowly and settled behind the early leaders, On the far turn, he quickened and swept to an easy 6+1⁄2 length win.

"[21] Despite never having raced in stakes company, Justify was subsequently ranked as one of the leading contenders for the Kentucky Derby, moving into seventh place in the March 12 NTRA poll.

But when McKinzie suffered a setback due to injury, Baffert decided to keep Justify at his home base for the Santa Anita Derby.

[24][25] On September 11, 2019, The New York Times reported that Justify failed a drug test for scopolamine after winning the Santa Anita Derby.

According to the veterinarian quoted in the New York Times article, the excessive amount detected suggested that it was used as a performance enhancer and was not simply a feed contaminant.

However, the California Horse Racing Board (CHRB) did not announce the positive and delayed making a decision on the case before ultimately dismissing it in August.

[26][27] Dr. Rick Arthur, the board's equine medical director, subsequently explained that their investigation suggested that the result was in fact due to feed contamination by jimson weed.

"[28] On December 1, 2023, Judge Mitchell Beckloff of the Los Angeles County Superior Court ordered CHRB stewards to issue a new ruling to state that Justify won the Santa Anita Derby with illegal medication in his system, which would disqualify the horse from the race.

[3] The order was the result of a lawsuit from Mick Ruis, owner of Santa Anita Derby runner-up Bolt d'Oro, who filed the litigation after stewards announced they were not required to disqualify Justify.

[3][4] On March 7, 2024, The Blood-Horse reported that the CHRB had agreed to a $300,000 settlement with Ruis to resolve all claims and would instruct stewards to issue a disqualification ruling.

[30] In April 2024 Justify's owners filed a notice of appeal, claiming that their absence as a party in the litigation between Ruis and the CHRB led to a denial of due process.

Justify broke well and used his early speed to establish good position near the rail going into the first turn, running a length behind Promises Fulfilled in a fast opening quarter of 22.24 seconds.

He was still impressed by Justify's performance, pointing out that the colt had been pushed hard by Good Magic and had also reacted greenly by jumping several puddles during the race.

"[43] On May 24, ESPN.com and the New York Times reported that Justify's breeding rights had been sold prior to the running of the Preakness to Coolmore Stud (which had owned his sire Scat Daddy) for $60 million.

[45] Baffert was the trainer of the prior Triple Crown winner, American Pharoah in 2015, and followed a similar training regimen with Justify at Churchill Downs until shipping to New York a few days before the Belmont.

"[49] The win made Justify the thirteenth winner of the American Triple Crown, and just the second horse to accomplish the feat while still undefeated.

Restoring Hope broke slowly from the starting gate but quickly headed for the lead in between horses, cutting in front of Noble Indy and drifting wide entering the first turn.

Mike Repole, the co-owner of Vino Rosso and Noble Indy, told the Daily Racing Form that he was confused by seeing Restoring Hope "rush up like he was a Quarter Horse".

[51] On the other hand, D. Wayne Lukas, the trainer of Bravazo, found the situation "strange", but did not think Restoring Hope's actions affected the outcome of the race.

Connections of Bolt d'Oro sued the California Horse Racing Board in 2020 to disqualify Justify because of a positive test for scopolamine, which was found in jimsom weed that contaminates hay.

[63] Justify's win in the Belmont Stakes was named the NTRA Moment of the Year, chosen from events that illustrate "a range of human emotions as well as outstanding displays of equine athleticism".

[67] In 2020, Harlocap, the first foal of Justify, a colt, out of Bodemeister mare Mezinka, was born on April 20, in Kentucky' Breed First LLC farm.

Justify is also line bred on Northern Dancer through Storm Cat, Yarn, Nijinsky, Deputy Minister, Preach, and Baldski.

Further back, Justify's pedigree contains multiple line breedings on some of the greatest sires of the twentieth century, including Native Dancer, Nearco, and Man o' War.

Indy; descends from Count Fleet through Mr. Prospector and Primal Force, and has multiple crosses to War Admiral through Ogygian's daughter Myth, Personable Lady, and A.P.