Senate leaders of both parties are urging their colleagues to renew an expiring warrantless surveillance law before it lapses at midnight on Friday, as advocates of the law have argued that any expiration would mean going blind on a key source of counterterrorism information and other foreign intelligence.

That deadline adds pressure to senators not to vote for any amendments to the version of the bill that the House passed last week, since any changes would force the legislation to go back to the House rather than swiftly arriving on President Biden’s desk.

But the suggestion that the tool itself would simply lapse on April 19 is significantly misleading. A national security court this month granted a request from the government that allows the program to operate for another year, even if the law, known as Section 702, expires. Still, it is true that such an expiration could lead to smaller gaps in collecting some messages.

Here is a closer look.

What is Section 702?

It is a law that authorizes the government to collect, without a warrant and from U.S. companies like AT&T and Google, messages of foreigners abroad who are targeted for intelligence or counterterrorism purposes.

The idea is that in the internet era, foreigners’ communications are often handled by domestic companies. But it is controversial because the government also sweeps up messages of Americans to and from those foreign targets.

The law traces back to a warrantless wiretapping program that President George W. Bush secretly created after the terrorist attacks of Sept. 11, 2001. It violated the Foreign Intelligence Surveillance Act, or FISA, which requires warrants for national security wiretapping on domestic soil.