At a rally for President Trump at the Phoenix Convention Center on Aug. 22 in Phoenix, the announcer introduced to the stage, "The secretary of the U.S. Department of Housing and Urban Development, Dr. Ben Carson." (The Washington Post)

This article has been updated.

Right before Ben Carson took the stage at President Trump’s rally in Phoenix on Tuesday night, the announcer introduced him.

“The secretary of the U.S. Department of Housing and Urban Development, Dr. Ben Carson,” the voice intoned, prompting cheers from the audience.

And, as simply as that, a law was likely broken.

There are a lot of ways in which the federal government could be used to reward political friends and allies, of course, appointments being just one example. But the power of the government can also be leveraged to political advantage. Imagine a candidate who appeared at a campaign rally to be endorsed by the heads of each branch of the armed forces, for example. That would carry a lot of weight.

In 1939, Franklin Roosevelt signed the Hatch Act into law, a measure meant to preserve the impartiality of public servants. “The law’s purposes,” the Office of Special Counsel’s website explains, “are to ensure that federal programs are administered in a nonpartisan fashion, to protect federal employees from political coercion in the workplace, and to ensure that federal employees are advanced based on merit and not based on political affiliation.​​​​”

Among the prohibitions included in the Hatch Act is one prohibiting Cabinet secretaries from leveraging their positions for a political cause. That means that the head of, say, the Department of Housing and Urban Development can’t appear at a campaign rally in a way that implies he’s doing so in an official capacity. Say, by being introduced with his official title.

The act “prevents government employees from using their position and their station to promote candidates or political parties,” explained Larry Noble, senior director of the Campaign Legal Center. “The idea is that the government, once it’s in government, is supposed to be nonpartisan. It’s really to prevent the abuse of power.”

You might be wondering why this would apply to a Cabinet secretary appearing at an event for the president more than three years before he’s up for reelection. The reason, quite simply, is that Trump’s rallies over the past few months have, in a legal sense, been rallies on behalf of his 2020 bid.

In order to avoid criticism for the cost and tone of the events, the bills have been paid by a reelection campaign organization that was formed back in January. Meaning that the rally in Phoenix was a campaign event. And meaning, Noble said, that Carson should not have been introduced with his official title.

“He should have told them in advance that they cannot use his title,” Noble said. “Once hearing the introduction, he should have made clear he was speaking in his personal capacity and not as secretary.” Carson didn’t.

Trump’s team should know better. It should know better because Trump’s social media director ran afoul of the Hatch Act in April when he tweeted a political call to action from his Twitter account. It was his personal account — but since his account identified him as an employee of the administration, it was considered to be a violation. What’s more, Carson’s predecessor at HUD, Julián Castro, was himself found to have violated the act when, in April of last year, he indicated during a news interview conducted in the department’s offices that he endorsed Hillary Clinton.

Punishment for a willful violation of the act could include removal of an official from his position. The Office of Special Counsel left punishment for Castro to his boss, President Barack Obama. In this case, it seems unlikely that any punishment would follow from Carson’s appearance, especially if left to Trump.

In normal times, rules like the Hatch Act serve a role similar to the rumble strips that line the shoulders of highways, warnings that you may be entering a danger area. In 2017, though, with an administration that’s breaking norms with regularity, it’s a bit like a smoke detector going off in a building near the epicenter of a nuclear blast.

“Some of these things, in the total scheme of things, in a normal presidency, you might raise it,” Noble said. “In a presidency where they’re doing all of these things, it’s relatively minor. But you hate to let it go, because this is what it’s all about in the end.”

Update: HUD spokesman Raffi Williams responded by email.

We don’t believe there was a Hatch Act violation. Dr. Carson’s travel and lodging were not paid for by the Department. Dr. Carson was there in his personal capacity. Additionally, he did not discuss HUD during his speech. We are unaware of what instructions, if any, were provided to the announcer. All other references during the event refer to him as Dr. Carson. In this instance he did not hear his name before he was cued to go on. We are consulting with our Ethics Office on the matter to ensure it doesn’t occur again.