As Philadelphia hosts a series of events this year commemorating the writing of the Constitution, local and federal officials have been assailed by a variety of political groups charging that the constitutional right of free speech is being squelched.

"The irony is that {bicentennial planners} are throwing a birthday party and not inviting the honored guest: the Constitution," said American Civil Liberties Union lawyer Stefan Presser, who has represented a coalition of activist organizations in legal action against the authorities.

Philadelphia police and the U.S. Park Service have said they acted to ensure security and to prevent disruptions at public events, but critics believe their purpose is to keep patriotic displays free of dissent.

The controversy began May 25, when Vice President Bush and other dignitaries gave speeches at a ceremony in front of Independence Hall, the Constitution's birthplace. A group called The Pledge of Resistance, which opposes U.S. policy toward Central America, had hoped to get its message across.

Park police barred protesters from carrying signs or leaflets past security barriers, and people wearing antiadministration buttons, T-shirts, and arm bands were excluded from the festivities. Anyone wearing the emblem of We the People 200, the quasi-official organization coordinating the year-long celebration, was admitted to the area.

Pledge of Resistance then sued the park police, the Philadelphia police, and We the People 200.

Last week, a federal judge declared the police action at Independence National Historic Park "a clear violation of the Constitution" and prohibited the authorities from taking similar measures against future protesters.

"Obviously, the defendant Park Service personnel sought to prevent plaintiffs from expressing their dissenting views in any manner which might come to the attention of persons attending the vice president's speech, and which might detract from the mainstream patriotism reflected by the We the People 200 insignia," U.S. District Court Judge John P. Fullam wrote.

But Fullam's ruling did not put to rest activists' complaints about police conduct that Presser said "smacks of totalitarianism."

The judge refused to ban police surveillance of political activists, as the Pledge of Resistance had requested.

Apparently concerned that activists might engage in civil disobedience and threaten the public safety today when an estimated 200 members of Congress travel to Philadelphia for a special bicentennial observance, Philadelphia police "infiltrated" the Pledge, according to the judge's finding. An undercover officer secretly attended two or three of the organization's meetings, the judge said. Other groups also allege that their activities were monitored.

Representatives of the various groups emphasized that they are committed to peace, but Police Commissioner Kevin M. Tucker said it was important for his department to collect "intelligence" about a potentially difficult situation.

Hobart G. Cawood, superintendent of Independence Park, rejects the view that the conflict over freedom of speech and assembly has subverted the spirit of the bicentennial.

"It's the Constitution in action," Cawood said.