Why did the International Tennis Federation issue a statement Monday supporting chair umpire Carlos Ramos’ handling of the US Open women’s final?

Because he followed the rules.

Serena Williams, who lost to Naomi Osaka 6-2, 6-4, accused Ramos of sexism after he issued her three code violations. And the debate has raged since.

While there’s no doubt Williams has endured sexism and racism throughout her long and historic career, and that sexism continues to exist in tennis, it doesn’t mean bias was at play on Saturday.

Before Ramos issued the third code violation, which cost Williams a full game, she had called Ramos, a veteran at Grand Slam tournaments, a “liar’’ and a “thief.’’

“Do you know how many other men do things that are much worse than that?” she said during an on-court discussion with US Open officials.

Now, let’s check the 2018 Official Grand Slam Rule Book.

“… verbal abuse is defined as a statement about an official, opponent, sponsor, spectator or other person that implies dishonesty or is derogatory, insulting or otherwise abusive."

To call an umpire a liar and a thief clearly implies dishonesty.

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As for the notion that men get away with saying and doing much worse, that has not always been the case in Ramos’ history as a chair umpire.

During the 2016 Olympics, Ramos issued a code violation to Andy Murray after thinking Murray had called Ramos “stupid.’’ Murray later claimed he said “stupid umpiring,’’ not “stupid umpire.”

During a fourth-round match at the 2017 French Open, Rafael Nadal lost a first serve after Ramos issued a code violation for Nadal taking too much time. Nadal later fired back, saying Ramos would “never chair another of his matches again.”

In July at Wimbledon, Ramos issued Novak Djokovic a code violation for unsportsmanlike conduct because Djokovic threw his racket to the ground.

Let's not forget how the controversy began for Williams. In the second set, Ramos saw Serena’s coach, Patrick Mouratoglou, signaling to her and Ramos issued a first code violation — and a warning — for the prohibited coaching from the stands. (In the 2016 French Open, Ramos also issued Serena's sister, Venus, a warning for coaching.)

Mouratoglou on Saturday admitted he was coaching and said Ramos should have quietly warned Williams to tell Mouratoglou to stop.

“That’s what umpires do all year,” the coach said, “and it would have ended there, and we would have avoided a drama that was totally avoidable.”

But assessing code violations for coaching is not uncommon, according to information provided by the ITF. Of the 31 code violations assessed during the three Grand Slams before the US Open, 11 of them were for coaching — more than any other code violation.

Because Williams was issued a warning for the coaching violation, she was immediately assessed a code violation when she slammed her racket onto the court and received a point penalty.

During the three previous Grand Slams — the French Open, Wimbledon and Australian Open — men were assessed 59 code violations, almost twice as many as the women. The men were issued violations for coaching nine times and the most common violation was abuse of racket/equipment 19 times.

What got most seriously abused at the US Open — Ramos’ character.

Women deserve better from professional tennis, but Ramos deserved better from Williams, too.