NASHVILLE — Drivers in Tennessee can no longer be charged with violation of the implied consent law if they refuse to submit to a blood or urine test to determine their blood alcohol content.

A new state law took effect Saturday, eliminating implied consent for blood and urine tests in DUI cases. Prior to Saturday, state law held that anyone driving a motor vehicle in Tennessee has given consent to a blood, breath or urine test — at law enforcement officers’ discretion — to determine their blood alcohol content. A refusal to submit to those tests resulted in violations, with penalties ranging from license revocation to jail time and fines, depending on extenuating circumstances.

However, the U.S. Supreme Court last year ruled implied consent laws unconstitutional, saying that states cannot criminalize a DUI suspect’s refusal to submit to a forensic test. While drivers in all 50 states can have their licenses revoked for refusing those tests, the Supreme Court’s decision addressed the 11 states — including Tennessee — that imposed those additional criminal penalties, such as jail time and fines, for such refusals.

The Supreme Court’s decision meant that law enforcement officers need a search warrant before requiring drivers to submit to blood tests. However, the court ruling stopped short of requiring a warrant for breath tests, which are generally considered less intrusive.

Faced with the potential for lost federal revenue, Tennessee had little choice but to amend its implied consent law. Under the new law, drivers must give consent for a blood test, or a warrant must be obtained.

The new law still allows implied consent for warrantless breath tests. However, courts do not have the authority to revoke a driver’s license or require an interlock device if the driver is not informed of the consequences of refusing to submit to a breath test.

In addition, several other noteworthy laws took effect on Saturday. Among them:

The Improve Act: Gov. Bill Haslam’s chief legislative effort in 2017 was the Improve Act, which increases the state’s tax on gasoline and diesel fuel by six and 10 cents per gallon over the next three years. The first four-cent increase took effect on Saturday, and is expected to add nearly $250 million to the Department of Transportation budget to address a $10 billion backlog in road projects across the state.

Guns in public: Counties and cities that post signs prohibiting firearms in public facilities will now be required to allow handgun permit holders to carry guns in those places or install new security measures, such as metal detectors or armed guards. However, there are some exceptions: parks that are used by schools, schools themselves and public libraries. The law does not apply to municipal parks, such as Oneida City Park, because the state passed a law in 2015 that prohibits cities and counties from banning handgun permit holders from carrying guns in parks.

Guns on boats: People who can legally own firearms can now possess firearms — loaded or unloaded — on boats, regardless of whether they have a handgun carry permit. The new law expands a previous law, which allows people to possess firearms in automobiles. Government boats and privately-owned boats with signs prohibiting firearms are excluded from the new law.

Move over: Tennessee’s Move Over Law has been expanded to include any vehicle on the shoulder of the road, in the emergency lane or in the median. If drivers encounter a vehicle in those areas of the roadway with its emergency lights flashing, the law requires they make a lane change and slow down. Violations of the law are punishable by fines of up to $500 and possible jail time. Previously, the Move Over Law applied only to first responder vehicles.

Abortion ban: A new law makes it illegal for a doctor to perform an abortion on a woman who is more than 20 weeks pregnant, if it is determined that the woman is carrying a viable fetus. There are exceptions for situations in which the woman’s life is in danger or when it has been medically determined that the fetus has no chance of surviving.

Enhanced punishment for attacking cops: Defendants who are convicted of violent crimes where their victims were specifically targeted because they were uniformed law enforcement officers or military service members will now face enhanced punishment. A separate law now requires immediate family members of first responders killed in the line of duty to receive health insurance benefits for two years after the first responder’s death.

Flag displays: Beginning Saturday, homeowners associations in Tennessee cannot legally prohibit homes from displaying the American flag or military flags.