John Judge
© Melissa Golden for The Wall Street JournalJohn Judge says Dallas is preventing conspiracy theorists a permit to gather at Dealey Plaza, the assassination site.
Dallas - Officials in the city where President John F. Kennedy was gunned down Nov. 22, 1963, want to observe the 50th anniversary of that day with a celebration of his life.

The city plans a ceremony that would include readings from Kennedy speeches by historian David McCullough and military jets flying over Dealey Plaza, where the 35th president was shot.

But some who believe the assassination was a conspiracy involving high-ranking U.S. officials say their views shouldn't be excluded from the commemoration.

"It's absurd to move the discussion of his death to another moment," said John Judge, executive director of the Coalition on Political Assassinations, a Washington, D.C., nonprofit that studies 1960s murders of public figures. "Our First Amendment rights are being violated."

Mr. Judge, 65 years old, said conspiracy-theory proponents have gathered at Dealey Plaza every Nov. 22 since 1964. Next year, he added, will be the first that Dallas hasn't granted a permit for the meeting, which usually involves a moment of silence and a few speeches.

He said the city should move its ceremony elsewhere, adding that his group's members would find a way to disseminate their theories during the city event, possibly even dropping protest banners from nearby buildings.

"The world and the nation turned against Dallas," Mr. Payne said.

John F. Kennedy And Eternal Flame
© European Pressphoto AgencyJane Kennedy visits the plaza on Nov. 22, 2011.
The animosity has faded, but Dallas remains closely linked to the assassination, a topic that continues to fascinate many. Over 70% of Americans believe that more than one person was involved in the killing, according to a 2003 Gallup poll.

"There are so many possible plotters," said Kathy Olmsted, a history professor at University of California, Davis, who has studied conspiracy theories about the U.S. government. "It becomes some sort of parlor game to people."

On any given day, dozens of tourists from around the world track the route followed by Mr. Kennedy's motorcade through downtown Dallas, taking pictures in front of the white X that marks the spot where the first bullet hit the president. The Sixth Floor Museum, housed in the building from which Lee Harvey Oswald fired, gets more than 300,000 visitors a year.

Dallas is sprucing up Dealey Plaza, repairing the chipped paint on its pergolas and covering up graffiti, in preparation for the ceremony, which will start with church bells and end with a benediction. Private funds will cover the cost, estimated at $1 million, with half of the amount set aside for security. People who wish to attend the ceremony will need to sign up for free tickets; the number of tickets and how they will be distributed remains unclear.

For those who can't get tickets, the event will be broadcast on giant screens around the city. Demonstrators will be allowed to gather in front of City Hall a few blocks away.

But Pete Johnson, a 58-year-old pharmacist from Columbus, Ohio, who studies the Kennedy assassination in his free time, has launched Occupythegrassyknoll.com to urge supporters to descend on the plaza for the ceremony. Some conspiracy theorists believe a second shooter fired at Mr. Kennedy from a patch of grass in the plaza.

"It's a controversial historical event," he said, "and they need to allow that controversy to be expressed."