The American Civil Liberties Union filed suit in U.S. District Court yesterday to block the Interior Department from restricting demonstrations in front of the White House.

The ACLU seeks to block implementation of a new rule, which went into effect last Friday, prohibiting protesters from leaving parcels in front of the White House for more than an hour or using signs that are not held by hand. The rule is aimed at demonstrators who maintain a constant vigil with bags and equipment in front of the White House.

In asking for a preliminary injunction to block the rule, the ACLU said the regulation infringes on protesters' First Amendment rights to assemble and express themselves freely. In addition, the ACLU said the government has failed to publicize the rule and obtain public comment before putting it into effect, as required by law.

The Park Service had described the new rule as an interim measure until comments could be obtained. It becomes permanent May 23. According to the notice in the Federal Register, the types of signs that are prohibited "represent potential threats to the security of the area," the president, and the White House, because they could be used to conceal weapons or explosives.

Three perennial demonstrators, Edward Saffron, Concepcion Picciotto and Robert Dorrough, already have been arrested under the new regulation, according to the ACLU. The rule carries a penalty of six months in jail or a fine of $500, or both.

Saffron and Picciotto were held for about three hours Wednesday and released after they posted $50 bond, the ACLU said in the suit filed on their behalf. Dorrough was released on personal recognizance.