Federal agents will be allowed to confiscate any marijuana found even in vehicles driving through checkpoints 100 miles from the Mexican border.

After more than a year after Californians overwhelmingly voted to legalize cannabis, the law will go into effect on Monday. Residents and visitors of the state will be allowed to possess small amounts of marijuana without fear of arrest. Well, that’s not totally true.

According to a report by the Associated Press, cannabis possession still will be prohibited at eight Border Patrol checkpoints in California. Federal agents will be allowed to confiscate any marijuana found even in vehicles driving through checkpoints 100 miles from the Mexican border.

“Prior to Jan. 1, it’s going to be the same after Jan. 1, because nothing changed on our end,” Ryan Yamasaki, an assistant chief of the Border Patrol’s San Diego sector, told the Associated Press. “If you’re a federal law enforcement agency, you uphold federal laws.”

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This tension between the federal government and legal marijuana states does not just apply to California. The Border Patrol operates 34 permanent checkpoints along the Mexican border and an additional 103 “tactical” stops, typically cones and signs that appear for brief periods, the Associated Press reports.  Eleven of those checkpoints are located inland in California, and agents still to confiscate small amounts of cannabis from motorists.

According to the American Civil Liberties Union:

Border Patrol agents routinely ignore or misunderstand the limits of their legal authority in the course of individual stops, resulting in violations of the constitutional rights of innocent people. These problems are compounded by inadequate training for Border Patrol agents, a lack of oversight by CBP and the U.S. Department of Homeland Security, and the consistent failure of CBP to hold agents accountable for abuse. Thus, although the 100-mile border zone is not literally “Constitution free,” the U.S. government frequently acts like it is.

The Government Accountability Office reported last month that roughly 40 percent of cannabis seizures at CBP checkpoints from 2013-2106 was from US citizens carrying one ounce or less. California law allows for possession of one ounce.

Earlier this year, US Attorney General Jeff Sessions, a longtime opponent of marijuana legalization, said he was taking a close look at federal enforcement. At times, he has been critical of President Barack Obama’s lenient approcach to cannabis.

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In about an hour, three raised enough suspicion to be ordered aside for a thorough vehicle search.

About two-thirds of the US population lives within the 100-mile zone — that is, within 100 miles of a US land or coastal border. That’s about 200 million people. Connecticut, Delaware, Florida, Hawaii, Maine, Massachusetts, New Hampshire, New Jersey, New York, Rhode Island and Vermont lie entirely or almost entirely within this are.

Nine of the 10 largest metropolitan areas fall within this zone: New York City, Los Angeles, Chicago, Houston, Philadelphia, Phoenix, San Antonio, San Diego and San Jose.