(CNN) Spencer DesAuteles was standing in a crosswalk at a protest against President Donald Trump's travel ban in January when he and two other people were hit by a car. The Tennessee resident, who was working as a volunteer to keep protestors safe from traffic, said he had the legal right of way when a driver rolled through the intersection.

"I stopped in front of this car," DesAuteles recounted. "We made eye contact. The driver stopped and then just decided to slowly drive through me. There was nowhere else to go. It was get out of the way or get under the wheels of the car. So we got driven on the hood of this car for some distance."

No one was injured in the incident, and the Metro Nashville Police Department concluded there were misunderstandings on both sides and therefore no reasons to pursue charges. But under a bill in the state legislature, drivers who do injure protesters blocking traffic would be exempt from civil liability so long as they were "exercising due care."

"The sponsor was very clear that the wording of the bill is not to say that it's OK to go and hit people with your car," DesAuteles said. "But that's the way that people are reading it. The only way it's being read by the vast majority of people is: 'I can hurt protesters and get away with it.'"

Republican state Rep. Matthew Hill, the bill's sponsor, did not respond to a request for comment on the legislation, which failed to move out of a House subcommittee, although a companion bill is pending before a Senate subcommittee. But the measure is just one of several being considered across the country as state lawmakers react to protests against President Donald Trump and his policies, instances of police brutality, the Keystone XL and Dakota Access pipelines and other issues that could continue to draw national attention.

So far, lawmakers in at least 18 states have proposed legislation that would make it harder to protest, create harsher penalties for protestors who are arrested, and, in two states, remove liability from drivers who accidentally injure protesters on roadways.

Proponents of the bills say they are commonsense measures to ensure public safety after the high-profile protests against the Dakota Access pipeline near Cannonball, North Dakota, and against the police shootings of Michael Brown in Ferguson, Missouri, and of Jamar Clark and Philando Castile in the Minneapolis-Saint Paul, Minnesota, area.

But the trend is alarming to civil rights groups and others who say the measures would trample the public's First Amendment rights.

"Some of these bills are so egregious that you don't need a law degree to conclude they're unconstitutional," said Lee Rowland, an attorney for the American Civil Liberties Union, who has monitored state legislation for more than a decade.

The United Nations has also taken note, releasing a report by the special rapporteur identifying anti-protest bills in 16 states, which the report called "a worrying trend."

"We are concerned that the above-mentioned bills are incompatible with international human rights law and would unduly restrict the possibility for individuals to freely exercise their rights to freedom of opinion and expression, and peaceful assembly," it said. "If adopted, the pending bills could have a domino effect on other states, leading to a general crackdown on protests in the United States."

Under one bill in Missouri , wearing a mask or disguise while protesting would be a crime, while under another , in Oklahoma, trespassing on property containing critical infrastructure could land a perpetrator a fine of at least $1,000 and six months in jail, with intent to vandalize or actually damaging the structure bringing much stiffer penalties of a year in prison and at least a $10,000 fine or up to 10 years in prison and a $100,000 fine, respectively.

Meanwhile, state lawmakers in Georgia Iowa , Tennessee and Florida have pushed bills to boost penalties for blocking roads and highways or trespassing, with the Florida bill also exempting drivers from liability for unintentionally injuring or even killing protestors who do so.

Last month, the Tennessee legislature passed a bill sponsored by Republican state Rep. Jimmy Matlock that would make it a misdemeanor to obstruct streets and highways in a way that restricts emergency vehicle access, quadrupling the fine to $200; Republican Gov. Bill Haslam signed the bill earlier this month.

In Minnesota, legislators are considering two highway-obstruction bills and a measure that would allow protestors to be sued for the cost of policing their protests.

Republican state Rep. Nick Zerwas, who had a hand in all three bills, said he coauthored one of them after hearing how his constituents were affected when protesters shut down freeways, a tactic he called "the go-to protest move."

"When you shut down a freeway or you close an airport, it has a real impact and it hurts real people," Zerwas said.

In the last two years, protesters have shut down Interstate 94 in the Minneapolis-St. Paul area after the police shootings of Jamar Clark and Philando Castile and also after Trump's election victory.

"If you stand in the middle of a freeway and try to block a freeway, you deserve to go to jail," Zerwas said. "It's really that cut and dry."

The measures would make obstructing highways, airport entrances or transit vehicles a gross misdemeanor punishable by up to a year in prison or a $3,000 fine for non-violent offenders or by up to three years in prison or a $5,000 fine for violent offenders.

"The reality is that you have no First Amendment right to free speech or assembly on the center lane on the freeway or the entrance to an international airport or the middle of a train track," Zerwas said. "It's already against the law to be there; all we're doing is increasing the penalty. We are not taking a single protest or free speech activity that is currently legal and making it illegal by passing these bills."

The bills are part a public safety package of legislation , Zerwas said, adding he is "very hopeful" Democratic Gov. Mark Dayton would ultimately sign the legislation. The third bill, to allow protesters to be sued for the cost of policing, is not expected to pass.

Meanwhile, in late March, the governor of South Dakota signed a bill that caps the number of people allowed to gather on public lands at 20.

Matt Konenkamp, a policy adviser to South Dakota Gov. Dennis Daugaard, told CNN the law is meant to deal any protests over the planned construction of the section of the Keystone XL pipeline that will run through South Dakota.

"It patches a hole in our existing law relative to emergency situations," Konenkamp said. "If we're forced to declared an emergency in response to a public safety need that's triggered by people that are gathering for peaceful protests, to object to the TransCanada pipeline, we will have this hole patched in our existing law."

The law says if it is necessary to "preserve the undisturbed use of the land" or if "the land may be damaged," the state commissioner of school and public lands can restrict gatherings at the request of the governor and the sheriff who has jurisdiction. It also makes obstructing roadways a misdemeanor crime.

"We support people's right to protest and certainly, in this instance, the Native Americans' right to peacefully and prayerfully gather and note their objections with," Konenkamp said, referring to Keystone XL protests. "Second, I would say that there are time and place restrictions on first amendment rights."

The Arizona Senate also passed legislation targeting protest groups. The bill , which stalled in the state House and is not expected to pass, would allow law enforcement officials to go after organizers of any protest that turns violent, even if the violence was caused by a single attendee. The measure would accomplish this by making rioting a crime that can be prosecuted under the state's racketeering laws and by expanding the definition of rioting to include an action that "disturbs the public peace or results in damage to the property of another person."

Opponents of the bill say it would be a clear violation of due-process rights and the presumption of innocence.

"The fact that some other human makes a decision to violate the law does not make you a criminal, and the problem with that law is that it views every protestor with criminal suspicion," said the ACLU's Rowland. "So while rioting is not protected, the problem with that bill is it took every protester and rounded them up to a rioter effectively if one person makes the choice to break the law."

ACLU affiliates are working with community partners to oppose the bills in all 18 states, Rowland said, adding that the National Lawyers Guild and Amnesty International are also engaged in the process.

"These bills aren't just unconstitutional," Rowland said. "They're also a betrayal of American values."