(WJET/WFXP/YourErie.com) — With the Pennsylvania State Police announcing a DUI checkpoint scheduled for Memorial Day weekend in Erie County, JET 24/FOX 66 reached out to the Northwest Pennsylvania chapter of the American Civil Liberties Union (ACLU) for guidance.

The Fourth Amendment of the United States Constitution protects people from “unreasonable searches and seizures,” but despite some concerns that the DUI checkpoints violate that amendment, both the commonwealth’s Supreme Court and the Supreme Court of the United States have allowed for DUI checkpoints.

“They’ve ruled that the suspicion-less checkpoints for the purpose of public safety are constitutional,” said Sara Rose, the deputy legal director for the ACLU of Pennsylvania. “In Pennsylvania, there are certain requirements the police have to follow — for example, the checkpoints must be methodical, so it’s not up to the officer’s discretion. Pulling people over at random is not constitutional.”

PSP also must advertise in advance, with signs announcing the upcoming checkpoint. That leads to another question: if someone encounters signs announcing an upcoming checkpoint, can they avoid the checkpoint?

Absolutely, the ACLU says.

“Courts have said that if somebody turns onto a sideroad or makes a legal U-turn — and they’re turning off the road perhaps to avoid the checkpoint — that doesn’t provide probable cause to pull that person over,” Rose said, but that comes with a caveat. “The turn itself does not give them probable cause to stop you, but for people who drive all the time, maybe you don’t always remember to use the turn signal before changing lanes… It’s easy to find a reason to stop people.”

Motorists may choose to simply go through the checkpoint. Rose said drivers can expect the checkpoint to be brief. A driver will be asked to supply their license. They may also be asked to supply vehicle registration and insurance. A typical question, Rose said, is “Have you been drinking?”

“The law is that you can say, ‘I don’t want to answer that question,’ but then the police might ask you to take a breathalyzer test,” Rose said. “The fact that a person refuses to answer doesn’t provide a reason, but police might look at you a little more curiously.

“And if you lie, it’s also very problematic.”

Rose noted that the checkpoints legally are not allowed to be a “fishing expedition.”

“Checkpoints for drugs are unconstitutional,” Rose said. A sober driver who has drugs in a vehicle is not considered a driving hazard, she explained. “(The sobriety checkpoints) are about public safety and to determine if somebody is driving under the influence in a dangerous way.”

It’s also not an opportunity for the police to search vehicles.

“They can’t search a car without reasonable suspicion to believe they’ll find evidence of a crime,” Rose said. “If somebody gets pulled over and they have something in plain view — like on the dashboard — that indicates they may be involved in a crime, like evidence of illegal drug use, then the police would have reasonable suspicion to search the vehicle.”

A driver that has been drinking and is found to be over the legal limit in a DUI checkpoint will “most likely be arrested,” Rose said. “At that point, it’s the same advice we give to everybody who is under arrest — don’t say anything to the police until you have a chance to speak to an attorney.”

But again, the checkpoints have been upheld in the nation’s highest courts, they’re brief, and they abide by certain limits. A law-abiding, safe driver should be able to pass quickly through a checkpoint.

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“It’s never helpful to argue with the police. People do have a right to record on their cellphone encounters with the police, but being cooperative is the best advice I can give,” Rose said. “If you disagree, the time to argue is in court and not at the roadside stop.”