Officers said he was visibly intoxicated when he was pulled over in the early hours of Friday in Josephine County.
According to TMZ, the 52-year-old's "impairment was obvious", and he "blew well over the legal limit", though it was not reported what number the breathalyzer actually recorded.
Markle Jr, who shares a father with the Duchess of Sussex, was reportedly then taken to the Grants Pass Sobering Centre, while his Chevy Silverado was impounded. Thomas Jr.'s sister Samantha added that her brother's "drinking is not related to Meghan".
Thomas Jr. told Radar exclusively their father saw the estrangement coming.
Markle's DUI arrest comes just days after he invited his half-sister and her husband, the Duke and Duchess of Sussex, to his upcoming spring wedding.
Meghan Markle's half-brother has been arrested by police in the United States for drink driving.
Speaking to the Daily Mail, Meghan's big brother - who is marrying his fiancée, Darlene Blount in March - revealed that he'd sent an official wedding invitation to Meghan and Harry. "Meghan Markle is obviously not the right women (sic) for you", he wrote.
Thomas confirmed he hoped "our wedding will bring the family closer together".
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