Extremism occurs among the political left and the political right.  But some would have you think that violent extremists are all conservatives.

I know to take death threats seriously.  My home was under special police watch during part of my 14 years as a U.S. Congressman.  Eventually, a man went to prison for threatening to kill and dismember me because I opposed the legalization of marijuana.

However, real threats should not be conflated with harassment.  Joining them into a combined number is a dishonest political effort to sway public opinion by making the number of threats seem larger.  Likewise, it’s wrong to give unbalanced attention to threats against Democrats with little regard to threats against Republicans.

After the health care vote, Democratic lawmakers Bart Stupak of Michigan, Louise Slaughter of New York, and Tom Perriello of Virginia reported threats.  Rep. Betsy Markey (D-CO) asked for police to watch her home.  Republican leaders like House Minority Leader John Boehner (R-OH) immediately condemned these threats, as did Tea Party groups.

Politico reported, “There hasn’t been any hard evidence . . . but Democrats have tried to draw the link between the harassment and the sometimes-inflammatory rhetoric that tea partiers and Republicans deployed in opposing the health care overhaul.”

Lack of evidence did not stop some from depicting political opponents as dangerous.

Rep. Chris Van Hollen (D-MD) accused protesters of “stoking the flames” of violence.  Rep. James Clyburn (D-SC) accused Republicans of “aiding and abetting . . . terrorism.”  President Obama used the claims for a fundraising appeal.

But where was their outrage about threats to kill Sen. Jim Bunning (R-KY) only three weeks prior?  Bunning was menaced for filibustering against $13 billion in deficit spending to expand unemployment benefits.  And how about House Republican Whip Eric Cantor (R-VA), who opposed the health-care bill?  When a bullet was fired into his office window, Cantor reported it to the police—not the media—to avoid inciting violence.

Regardless of how extreme the new health-care law may be, it’s wrong to threaten or commit acts of violence over it.  Selective condemnation of violence is also wrong and should not be used to malign people for partisan purposes.

Overheated rhetoric also knows no political bounds.  In an MSNBC discussion of civility and threats in politics, progressive host Ed Schultz didn’t like it when I mentioned his February statement about former Vice President Dick Cheney’s heart, “We ought to rip it out and kick it around and stuff it back in him.”  Ed now defends his words as a metaphor about heart transplants and who receives health care.  But if the left feels free to use such figures of speech, why do they condemn the language of the right?

From representing Oklahoma City in Congress, I know that Timothy McVeigh’s deadly federal-building bombing was not the act of a mainstream political activist.  Those on the left tend to overlook another mass murderer, the Unabomber Ted Kaczynski, who sent 16 deadly package bombs to advance his extreme environmentalist throwback agenda.  They also ignore the violent trashing of Seattle by socialist-leaning anarchists.

Republican and Oklahoma State Rep. Sally Kerns reported multiple death threats from homosexual activists because she criticized their lifestyle.  In California, many Proposition 8 supporters reported similar threats.  But gay rights activists mourned the murder of a gay leader—San Francisco Supervisor Harvey Milk—by a fellow Democrat.

Many more examples exist.  Violence against political figures is not new and the motives are diverse.  I’ll always remember seeing President John F. Kennedy in person a few hours before he was shot by a communist sympathizer in 1963.  One survey counted that nine U.S. presidents have been attacked (four killed), as have three presidential candidates, seven U.S. Senators, nine congressmen, eight governors, 11 mayors, and 17 state legislators.

The point is simple:  Extremism and violence historically exist on both ends of the political spectrum.  Nobody should seek to advance their politics—as we are witnessing now—by pretending that menacing fanatics are all at one end of the political spectrum.  Nor should occasional use of common metaphors (“hit list,” “targeting” politicians for defeat, etc.) be mistaken as threatening.

Obviously, many Americans are angry.  But anger need not lead to violence.  Those who mock groups like Tea Party protestors are often trying to provoke them—a provocation that must be resisted.

Like millions of Americans, I see the new health-care law as a danger to civil liberties, an overreach of federal constitutional authority, a job-killing mandate, and a step toward bankrupting America.  Most recent polls show that a majority of people oppose the measure.

The American way to change this is through quiet revolutions known as elections.  The controversy should be resolved in the political process.  Overheated rhetoric is protected as free speech.  But it’s over the line and wrong to suggest that either major party favors the use of violence instead.

Ernest J. Istook is a Resident Fellow at Harvard’s Institute of Politics this spring and a Distinguished Fellow at The Heritage Foundation.  He served as a U.S. Congressman for 14 years.