Last week’s Democratic convention was expertly choreographed for television. For the most part, the party exercised tight control over signage, especially as the week went on. There was MICHELLE on Monday, AMERICA on Tuesday, OBAMA on Wednesday, and HILLARY on Thursday, accompanied by a sea of flags, indoor fireworks, and a pre-rehearsed card stunt finale.

Those watching from home had to look hard to notice that some delegates — most of them supporters of Sen. Bernie Sanders — had brought in their own signs, many of them expressing opposition to the Trans-Pacific Partnership, a broad and controversial trade agreement. They did so against the wishes of Sanders himself, who urged his followers by email not to protest or demonstrate at the convention “as a personal courtesy to me.”

Most Sanders-pledged delegates obeyed, but not all. A significant minority participated in a walkout, chanted their own slogans, and battled with party loyalists to make their anti-TPP signs visible. Sanders opposed the TPP vehemently, saying that it was “designed to protect the interests of the largest multinational corporations.” Clinton, who praised the potential benefits of the TPP as secretary of state, has publicly expressed qualms about it as well. John Podesta, who chairs Clinton’s campaign, has said that she opposes a vote on the deal before the election and would seek “a new approach” as president.

On Thursday morning, the Arkansas Democratic Party refused to issue a daily floor credential to Frank Klein, an elected delegate from Arkansas. Klein had held up an anti-TPP sign during Obama’s speech the night before, as had delegates from Illinois, Florida, and elsewhere. But delegates from Arkansas, Bill Clinton’s home state, were seated in the front and near the center of the convention hall, making them especially visible to news photographers and TV cameras.

A video taken Thursday morning shows Klein engaging in a heated argument with state party officials. “I have the right to free speech,” Klein shouts in the video. “I am representing my people and what they want me to do, not what you want me to do.”

Klein was not able to enter the arena on Thursday and told journalist Rania Khalek about the dispute that night.

H.L. Moody, a spokesperson for the Arkansas Democratic Party, confirmed that the party had refused to give Klein credentials on Thursday. Moody told me that Klein had violated rule E.2, which allows the convention’s leadership to take actions “to preserve order” on the floor.

“The Democratic Party is not a public organization,” he said. “It’s a private organization with rules.” As for the TPP, “Mrs. Clinton is against it. Bernie Sanders is against it. I’m against it. The content of the sign is not the issue.”

Moody also said that Klein had discussed joining the Green Party after Clinton’s nomination — which Klein did not dispute. Moody said this was a possible violation of another party rule, which presumes delegates to be “faithful to the interests, welfare, and success of the Democrats.”

Lee Rowland, a senior staff attorney with the ACLU, said political parties are allowed by law to set their own rules and control the convention action. “At the end of the day, conventions are political theater,” she said. “The candidates have a First Amendment right to get their message out and show the cameras whatever they want to show them.”

Klein, who owns a canoeing business and campground on the Ouachita River, arrived home late Saturday after two days of driving and one night spent in Virginia. He said he was exploring his legal options. “I’m not going to lay down for these people,” he said. When asked about his vote, he said: “That’s what the curtain on the booth is for. I got a lot of thinking to do.”

On Wednesday night, I had watched as floor whips and state party officials asked Illinois delegates to hand over their TPP signs — and then took pictures of those who refused to comply. Dan Johnson, a Sanders delegate, attorney, and lobbyist who helped organize his fellow Sanders delegates for the Illinois state party, told me that the ones who were continuing to protest were acting like “petulant adolescents.” “They’re only on this floor because of Bernie Sanders,” he said. “By acting like little assholes, they are making his revolution harder to achieve.”

Jeanne Marie Dauray, an Illinois Sanders delegate, captured protesters and convention staff on Twitter:

Delegates hold up anti-TPP signs on the floor during Day 1 of the Democratic National Convention.