Legalization Framework Under the Immigration and Nationality Act (INA) [November 5, 2019] [open pdf - 1MB]
From the Document: "The population of unlawfully present aliens in the United States numbers between 10 million and 12 million, according to recent estimates. The Immigration and Nationality Act (INA) takes three primary approaches to regulating this population: removal, deterrence, and--to a lesser extent-- legalization. Legalization, as used here, means the granting of a lawful immigration status to an unlawfully present alien so that he or she is no longer subject to removal under the INA. Put differently, an unlawfully present alien 'legalizes' by obtaining lawful permanent resident status (LPR or 'green card' status) or any other status (such as a nonimmigrant status) that extinguishes the statutory basis for his or her removal. The INA takes a generally restrictive approach to legalization. During much of the 20th century, a statutory provision called 'registry' allowed unlawfully present aliens to obtain LPR status based on their long-standing presence in the United States. If unlawfully present aliens had entered the United States before a fixed cutoff date and satisfied other requirements, such as a lack of certain types of criminal convictions, they could apply to the Attorney General for LPR status. The registry statute is now effectively obsolete because its cutoff date, which Congress last updated in 1986, remains fixed at 1972."
CRS Report for Congress, R45993
Congressional Research Service: https://crsreports.congress.gov/