On Tuesday, conservative pundit Katie Pavlich told Fox News's Megyn Kelly that Black Lives Matter is now "a movement that promotes the execution of police officers." The day before, Bill O'Reilly and a Fox & Friends segment suggested Black Lives Matter is "a hate group." And last weekend, a Texas sheriff linked a deputy's death to "out of control" rhetoric from Black Lives Matter.

This criticism of Black Lives Matter, which aims to squash racial disparities in the criminal justice system, and its protests is becoming increasingly standard, with pundits on Fox News and elsewhere blaming Black Lives Matter for inciting violence against both police and civilians — despite the lack of evidence for the claims.

But this isn't a new tactic for opponents of nonviolent civil rights movements. Four decades ago, detractors tried the same type of argument against Martin Luther King Jr.

Martin Luther King was criticized for inciting "hatred and violence"

King, who's now widely seen as an advocate for peaceful protest, wasn't quite viewed that way by everyone during the 1960s.

A 1963 letter from eight white clergymen — which inspired King's famous response, Letter From a Birmingham Jail — told black protesters to stand down because they were inciting "hatred and violence" in Birmingham, Alabama. The clergymen warned about the effects the protests in Birmingham led by "outsiders" like King would have:

Just as we formerly pointed out that "hatred and violence have no sanction in our religious and political traditions," we also point out that such actions as incite to hatred and violence, however technically peaceful those actions may be, have not contributed to the resolution of our local problems. We do not believe that these days of new hope are days when extreme measures are justified in Birmingham… We further strongly urge our own Negro community to withdraw support from these demonstrations, and to unite locally in working peacefully for a better Birmingham. When rights are consistently denied, a cause should be pressed in the courts and in negotiations among local leaders, and not in the streets. We appeal to both our white and Negro citizenry to observe the principles of law and order and common sense.

These fears of King's tactics and rhetoric went all the way to the White House. While many now know of the March on Washington in 1963 — in which King gave his renowned "I Have a Dream" speech — as a peaceful event, the Kennedy administration at the time expected the absolute worst. Pointing to the occasional violence among some of the civil rights protests swarming the country, critics and skeptics worried that the march would turn into a huge race riot.

President John F. Kennedy's brother and then-US attorney general, Robert Kennedy, invoked many of these fears in justifying what amounted to a preparation for war in DC. According to Nick Bryant of BBC News, Robert Kennedy told his brother during a tense White House meeting, "Negroes are now just antagonistic and mad and they're going to be mad at everything. You can't talk to them. My friends all say [even] the Negro maids and servants are getting antagonistic."

"Negroes are now just antagonistic and mad and they're going to be mad at everything"

As Bryant reported, these types of warnings were taken so seriously that the federal government essentially mobilized all its resources to prepare for the worst, deploying troops, beefing up security, ramping up surveillance, and clearing jails for new arrests. "The mission went by the code-name Operation Washington," Bryant explained. "So heavy was the military build-up that one reporter observed that 'the city was transformed from the capital of a nation at peace to a nation at war.'"

In retrospect, these types of warnings and preparations seem ridiculous. The march and King's speech are now viewed as part of the most successful peaceful protests in US history, leading to significant changes like the Civil Rights Act of 1964 and the Voting Rights Act of 1965.

But these fears are very similar to those faced by civil rights protesters today. The Black Lives Matter protests have been largely peaceful, resulting in violence in only a very few occasions: While the Baltimore and Ferguson, Missouri, protests resulted in some rioting, the marches and demonstrations in dozens of other cities were so peaceful and event-free that they by and large didn't make the news. Yet that hasn't stopped Fox News pundits and other critics from labeling Black Lives Matter a "hate group."

Protests aren't perfect

All of this exposes a broader, underappreciated point: Protests are messy. When thousands or millions of people rise up in passionate demonstrations, there are going to be a few bad moments and groups that can be used to mischaracterize the cause. There were riots in the 1960s, just as there were some riots in Ferguson and Baltimore. There were calls for violence from some demonstrators back then, just as some Black Lives Matter protesters were filmed shouting "pigs in a blanket" at a recent Minnesota march.

As Kevin Drum wrote for Mother Jones:

People and groups have to be free to condemn abortion or police misconduct or anything else—sometimes soberly, sometimes not. And it's inevitable that this will occasionally inspire a maniac somewhere to resort to violence. There's really no way around this. It's obviously something for any decent person to keep in mind, but it doesn't make passionate politics culpable for the ills of the world. We can't allow the limits of our political spirit to be routinely dictated by the worst imaginable consequences.

The occasional violence didn't represent the civil rights movement in the 1960s and doesn't represent the Black Lives Matter movement today. But just as people latched on to a few bad examples to condemn and raise fears about the civil rights movement decades ago, critics are latching on to a few bad examples to admonish the Black Lives Matter movement today.

The reality is protests, like any gathering of large groups of people, aren't always going to be perfect. But they can lead to significant change: The civil rights movement of the 1960s led to the Civil Rights Act and Voting Rights Act, and the efforts of Black Lives Matter are leading to police-worn body cameras and other efforts to increase law enforcement accountability.

Watch: Why it's so important to film police