President Biden has used a Cold War era law to allow more than 500,000 immigrants to remain in the U.S., according to a report.

The Biden administration's immigration policy has led to the most significant legal immigration wave in modern history, according to internal government records obtained by CBS News. Federal officials are using a decades-old provision in federal law that gives officials the authority to grant parole to migrants, which lets them enter the country legally without a visa.

This has led to legal status for 541,000 immigrants from all around the world, based on court records and public documents.

The 1952 law has allowed federal officials to justify taking immigrants without visas if there is an "urgent humanitarian" cause or "significant public benefit." This legal status, although, is limited to two years, when the immigrants would then need to have their status renewed or obtain a visa.

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President Joe Biden walks along a stretch of the U.S.-Mexico border

President Biden has allowed more than 500,000 legal immigrants to move to the U.S. through a program aimed at reducing illegal immigration, according to a report. (AP Photo/Andrew Harnik, File)

The administration has used a series of global crises to justify this decision, most notably mass migration in Latin America, Afghans fleeing from Taliban rule and Ukrainians who fled at the start of Russia's invasion. Parole authority from the administration has been used to grant legal immigration status to 168,400 Latin American and Caribbean migrants, 141,200 Ukrainian refugees, 133,000 asylum-seekers at the southern border, 77,000 Afghan evacuees, and 22,000 Ukrainians, according to government data.

The border crisis under Biden reached a peak last year, as more than 200,000 border encounters were logged for 10 months straight. The administration responded by looking for ways to allow legal migration without an appointment at the border.

The Uniting for Ukraine program was established early last year to allow the country's refugees to fly directly to the U.S., as opposed to the southern border, so long as they had a sponsor. A similar sponsor program was later launched for Venezuelans fleeing poverty and authoritative rule, which was expanded late last year to include those fleeing from Cuba, Haiti and Nicaragua.

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Joe Biden southern border immigration

The border crisis reached a peak last year under President Biden, with more than 200,000 border encounters for 10 months straight. (Jim Watson/AFP via Getty Image)

At the border, a program was launched that allowed migrants to set up appointments at a legal port of entry using a mobile app called CBP One.

Together, these programs from the administration are expected to continue this historic increase in legal immigration. The Ukraine program has no cap, the CBP One app allows more than 500,000 migrants each year, and the program for the select Latin American countries has an annual cap of 360,000 migrants.

A spokesperson for the Department of Homeland Security (DHS) emphasized the agency's use of parole has a strict process to ensure national security as they provide humanitarian assistance to migrants.

"Parole is only granted on a case-by-case basis to individuals who pass strict security vetting and meet certain criteria," a DHS spokesperson told Fox News Digital. "Those who do not have a lawful basis to remain in this country are being expeditiously removed, barred from reentry for five years, and potentially subject to criminal prosecution. More individuals have been removed or expelled than paroled in the last two years, and the conflation of very different parole processes that serve very different purposes is misleading and wrong." 

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Biden and Mayorkas

President Biden greets Homeland Security Secretary Alejandro Mayorkas as he arrives to speak at the DHS 20th anniversary ceremony at DHS headquarters in Washington, D.C.

Twenty Republican-led states filed a lawsuit against the Biden administration's program for the Latin American countries in January, claiming it oversteps the authorities of Congress to regulate immigration parole powers.

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"The Department of Homeland Security, under the false pretense of preventing aliens from unlawfully crossing the border between the ports of entry, has effectively created a new visa program without the formalities of legislation from Congress," the states wrote. "The Department’s parole power is exceptionally limited, having been curtailed by Congress multiple times, and can be used ‘only on a case-by-case basis for urgent humanitarian reasons or significant public benefit.’"