DENVER -- The battle between First Amendment rights and the protection of the public met head-on Tuesday in a federal courtroom.

Protesters argued they should be able to get within sight and earshot of delegates to the Democratic National Convention.

They turned out for the trial wearing orange jail uniforms and with tape over their mouths.

Thomas Mestnik of Recreate 68, which plans at least five marches during convention week, said free speech means a group can be within sight and sound of where it wants its message to be delivered.

Recreate 68 co-founder Mark Cohen insisted his group was committed to peaceful and nonviolent demonstrations.

The American Civil Liberties Union of Colorado and more than a dozen advocacy groups argue in the suit that the parade route and demonstration zone mapped out by the city keep protesters from being seen or heard by delegates entering the Pepsi Center, where the convention begins Aug. 25. Denver and the Secret Service are named as defendants.

Denver's plan would allow protesters to get as close as a parking lot on the Pepsi Center's grounds during the first three days of the convention and they would have to leave by 3 p.m., about the time delegates are expected to begin arriving each day.

The Secret Service argued that the threats are real and the security steps are fair and prudent.

U.S. Secret Service agent Steven Hughes testified that terrorists could mingle among the protestors and if they get to close to the Pepsi Center they could launch a bomb or chemical weapon.

At the Pepsi Center, authorities plan to build a fence to surround an area where delegates, VIPs, former presidents, and others with credentials for the convention will pass.

"As delegates arrive, we want to offer them the opportunity to walk safely into the Pepsi Center," he said. "We don't extend our perimeter further than we believe is necessary."

Closing arguments were expected Thursday.