After the Sept. 11, 2001 attacks, many asked how the hijackers were able to enter the United States and live there undetected while plotting their strikes.

The Justice Department reported that at least nine of the 19 hijackers were in the United States legally, three had remained in the country even though their visas had expired, and that the government did not know how the other seven entered the United States. This discovery cast a spotlight on the Immigration and Naturalization Service, the government agency charged with tracking immigrants and enforcing immigration laws.

The resulting scrutiny of the INS exposed what experts said were weaknesses in the agency's ability to effectively determine whether a visitor remains in the U.S. after his or her visa expires. The Justice Department's Inspector General Glenn Fine testified before Congress on Oct. 11, 2001 that the system identifying those who overstay their visas "does not produce reliable data, either in the aggregate or on individual nonimmigrants." He said the system's errors stem from "missing departure records and errors in processing of the records."

INS Responsibilities Moved To Two New Agencies
In what proponents said was an effort to strengthen the government's ability to patrol its borders while better meeting the needs of immigrants and overseas visitors, the 2002 Homeland Security Act separated the Immigration and Naturalization Service's two roles.

Under the new structure, two new agencies under the Department of Homeland Security assumed the duties previously assigned to the INS, which had been part of the Justice Department.

Within the new department, the Bureau of Citizenship and Immigration Services is responsible for immigration, including issuing green cards and handling asylum requests.

The INS' enforcement responsibilities were transferred to the Homeland Security Department's Border and Transportation Security division.

Security Measures Already Enacted
The government already has moved to tighten U.S. immigration policy. The Enhanced Border Security and Visa Entry Reform Act, signed into law by President Bush in May 2002, will be implemented by the new Homeland Security Department. It requires that foreign visitors possess tamper-proof travel documents with biometric information, such as retinal scans or fingerprints. The U.S. Immigration system had not requested such information from the vast majority of visitors from other countries.

In addition, as part of the Enhanced Border Security and Visa Entry Reform Act, the FBI and CIA will be required to share information with the State Department, which issues visas.

The law also calls for the development of a computerized means of tracking foreign students. This system, the Student and Exchange Visitor Information System, began in January 2003. Attorney General John Ashcroft said in a news conference in May 2002 that the system would help verify that foreign students are indeed enrolled in school and thus would close a hole in the country's immigration system. When Sen. Dianne Feinstein, D-Calif., argued for increased tracking of foreign students, she used the example of Sept. 11 hijacker Hani Hanjour, who was enrolled in an English language course that he never actually attended.

Plans for the Homeland Security Department also include the development of an entry-exit system to record the arrival and departure of foreigners. INS rules proposed on Dec. 31, 2002 require that airlines, cargo ships, cruise ships, and most other vessels carrying crew or passengers provide detailed information on all of their passengers to immigration officials. The lists are designed to help ensure enforcement of U.S. Immigration laws.

The USA Patriot Act, enacted in October 2001, includes additional measures aimed at exerting increased control over the nation's borders. As part of the act, the Justice Department has already begun the first phase of the National Security Entry-Exit Registration System. This work was started by the INS and continued after its responsibilities were transferred to the new Department of Homeland Security on March 1, 2003.

The National Security Entry-Exit Registration System and the Student and Exchange Visitor Information System have been integrated into a larger Department of Homeland Security initiative -- the U.S. Visitor and Immigrant Status Indication Technology system that was launched on April 29, 2003. The system is scheduled to begin its first phase of operation at international air and sea entry points by the end of 2003.

On Sept. 11, 2002 the INS began fingerprinting nonimmigrant aliens who they say pose a potential security risk. The estimated 100,000 people per year who will be part of this program are also required to periodically register with the INS. According to a Justice Department statement issued in August 2002, this system "is the first step toward the development of a comprehensive entry-exit system applicable to virtually all foreign visitors."

-- Compiled by Karyn Schwartz for the Online NewsHour