Washington (CNN) -- Americans have always exercised their Democratic rights under the U.S. Constitution to speak out against the government.
Amid the bitter fight over health care reform, a round of hate-filled messages and sometimes violent actions toward members of Congress has prompted calls to ease up on the rhetoric.
Experts say that although protests against social issues such as health care reform are nothing new for the country, such reaction to a landmark bill's passing is uncommon.
"It's unusual that you get this kind of outrage and response to a piece of legislation," said historian Robert Dallek, author of the upcoming book "The Lost Peace: Leadership in a Time of Horror and Hope."
"Of course, it's being fanned in some ways by Republican leaders who keep saying majorities are against this legislation, when in fact there is a pretty even divide in the country, from what the polling data shows," he added.
And those polls indicate that while the country was somewhat evenly divided on the issue in the months leading up to the vote, there has been a bounce in favor of President Obama and the bill.
Throughout last summer and fall, health care reform protesters took to Washington and town hall meetings across the country. Signs at some protests, depicting Obama as Nazi leader Adolf Hitler or calling him a "witch doctor," created a heightened sense that the movement against health care reform had taken an ugly turn.
The recent "sleazy" behavior is highly alarming, CNN Senior Political Analyst David Gergen said.
"It is sleazy. But this whole thing has gotten to a level of nastiness that I don't think we've seen in some years," he said. "Just as the partisanship has become so hyper now, the rhetoric is so hyper."
Michael Murakami, a professor of political science at Georgetown University, said it's certainly not the first time the country has seen this kind of activity, "inspired by political events that touch a nerve."
"But it's seems like it's been the first time in recent memory that we've seen landmark legislation and also a kind of mass emotional response you get from these controversial but very landmark bills," Murakami said.
History has shown that controversial issues dealing with social or fiscal policies can be the sparks that ignite a flame in people. Here are some other notable events:
CNN Senior Political Analyst Gloria Borger said that a lot of the violence and threats now being reported are reminiscent of past legislation involving social issues, especially the crime bill signed by President Clinton.
The Violent Crime Control and Law Enforcement Act, the largest crime enforcement legislation in U.S. history, became law in 1994. It provided funding for hundreds of thousands of police officers, gave aid to crime-prevention programs and put restrictions on weapons, including firearms.
"After the crime bill passed, people [who felt there was strict] gun control in it ... felt the role of government was too huge. After that, you had Oklahoma City [federal building bombing]," Borger said.
A bomb ripped through the Alfred P. Murrah Federal Building in downtown Oklahoma City, Oklahoma, in 1995, killing 168 people.
Timothy McVeigh, an Army veteran, was convicted of planning the attack and setting off the bomb. He was executed in June 2001. Others, including Terry Nichols and Michael Fortier, are serving time for assisting in the crime and not warning about the attack, respectively.
A lot of the same anti-government anger was seen a couple of years before the bombing, namely in the shootout in April 1993 that started the siege of the Branch Davidian compound near Waco, Texas, by Alcohol, Tobacco and Firearms agents.
The government believed that the religious group, headed by David Koresh, had stockpiled weapons. A 51-day standoff ended when the FBI stormed the compound, and a group of buildings caught fire and burned to the ground, killing 80 people inside. Four ATF agents were killed.
Civil Rights Act
Going back even further, the Civil Rights Act of 1964 was controversial among many in the South. And although violence against blacks continued after the bill's passage, there was no discernable peak in reaction.
"After Lyndon Johnson passed the civil rights bill in 1964, he was apprehensive that there was going to be a violent protest against it in the South," Dallek said. "This proved to be wrong."
Dallek said Johnson assumed that if the change in racial relations was done through Congress instead of the courts, "it would be very difficult for Southerners ... to express opposition in a violent way. That proved to be right."
But Dallek said that a lot of the anger behind the health care protest isn't just about the issue but rather people channeling frustration with the economic climate.
"I think it's partly the fact that you have this recession, an economic problem that puts people further on edge than they are normally," he said. "I think there's an awful lot of anxiety about that out there. That fans the flames of agitation."
He likens those worries to fears in the 1930s with the Great Depression.
"Remember in the 1930s when you had such a dreadful economic downturn," he said, noting that a movement popped up that was "full of a kind of rhetoric and anti-Semitism and anti-government."
"It was an explosion of populist protests, one might say, that seems not entirely divorced from the kind of thing we're seeing now," he added.
The New Deal
Julian Zelizer, a presidential historian and CNN.com contributor, wrote that frustration with joblessness -- like the opposition to Obama's economic stimulus bill -- was also seen during the New Deal era.
"It is possible that continued frustration about jobs allows Democrats to target Republicans as an obstructionist party that has in fact hampered their efforts to revitalize economic growth," Zelizer wrote in the commentary. "During the 1930s, President Franklin Roosevelt understood that you could not have recovery without jobs. This is why he made public works programs the centerpiece of the New Deal."
The New Deal, which was passed by Congress under Roosevelt's presidency, was signed into law in 1933. The legislation included economic stimulus programs aimed at jump-starting the depression economy. Much like Obama's effort, the New Deal relied on providing relief for those suffering, helping in the recovery of the country's economy and urging reform of the financial system.
The New Deal, Dallek said, provoked the creation of the Liberty League, an organization "fiercely opposed to Roosevelt's New Deal as something that was going to destroy freedom in the country and destroy the Constitution."
Although they didn't revert to violence, there were "a lot of verbal explosions of what Roosevelt's New Deal was doing in the name of small government and reducing centralized authority in the country."