Check this out JP about some of the results in this country from the last amnesty.
A lack of detention space has allowed several terrorists who had no legal right to be in the country to be released into the country. For example, Ramzi Yousef, the mastermind of the 1993 World Trade Center Attack, did not have a visa to enter the country, but he applied for asylum when he arrived at JFK airport and because of a lack of detention space he was paroled into the country.
Past amnesties for illegal aliens have facilitated terrorism. Mahmud Abouhalima, a leader of the 1993 Trade Center bombing, was legalized as a seasonal agricultural worker as part of the 1986 amnesty. Only after he was legalized was he able to travel outside of the country, including several trips to the Afghanistan/Pakistan border, where he received the terrorist training he used in the bombing.LINK