This is a summary from THOMAS, the public domain database of the U.S. Congress:

(Sec. 411) Includes within the definition of "terrorist activity" the use of any weapon or dangerous device.

Redefines "engage in terrorist activity" to mean, in an individual capacity or as a member of an organization, to: (1) commit or to incite to commit, under circumstances indicating an intention to cause death or serious bodily injury, a terrorist activity; (2) prepare or plan a terrorist activity; (3) gather information on potential targets for terrorist activity; (4) solicit funds or other things of value for a terrorist activity or a terrorist organization (with an exception for lack of knowledge); (5) solicit any individual to engage in prohibited conduct or for terrorist organization membership (with an exception for lack of knowledge); or (6) commit an act that the actor knows, or reasonably should know, affords material support, including a safe house, transportation, communications, funds, transfer of funds or other material financial benefit, false documentation or identification, weapons (including chemical, biological, or radiological weapons), explosives, or training for the commission of a terrorist activity; to any individual who the actor knows or reasonably should know has committed or plans to commit a terrorist activity; or to a terrorist organization (with an exception for lack of knowledge).

Defines "terrorist organization" as a group: (1) designated under the Immigration and Nationality Act or by the Secretary of State; or (2) a group of two or more individuals, whether related or not, which engages in terrorist-related activities.

Provides for the retroactive application of amendments under this Act. Stipulates that an alien shall not be considered inadmissible or deportable because of a relationship to an organization that was not designated as a terrorist organization prior to enactment of this Act. States that the amendments under this section shall apply to all aliens in exclusion or deportation proceedings on or after the date of enactment of this Act.

Directs the Secretary of State to notify specified congressional leaders seven days prior to designating an organization as a terrorist organization. Provides for organization redesignation or revocation.