A branch of America's leading civil rights group is considering whether to represent the Klu Klux Klan in its attempt to adopt a highway in Georgia.

The state's branch of the American Civil Liberties Union told the Guardian that it had been approached by the KKK after authorities in Georgia rebuffed the white supremacist organization's bid to take responsibility for picking up the trash on Route 515.

Debbie Seagraves, executive director of the ACLU of Georgia, said it was researching the facts of the case before deciding to take it on. She expressed concern that the KKK's application had been rejected. "The law is pretty clear you may not deny participation in a program like this – that is run by the state – based on the mission and the message of the organization. It's a free speech issue," she said.

The International Keystone Knights of the KKK in Union County applied to the state's adopt-a-highway program along Route 515 in May. Groups that are approved by the state volunteer to pick up trash along a stretch of road, and are recognized in a sign posted near the site.

Transportation department officials said in a statement Tuesday they would deny the KKK group's application, adding that the program is aimed at "civic-minded organizations in good standing".

The statement reads: "Promoting an organization with a history of inciting civil disturbance and social unrest would present a grave concern to the department.

"Issuing this permit would have the potential to negatively impact the quality of life, commerce and economic development of Union County and all of Georgia."

Seagraves expressed surprise at the decision. "I'm concerned the decision makers of the state thought that this was OK: it's viewpoint discrimination."

She said the first amendment of the US constitution was intended specifically to protect the free expression of unpopular views. "Even if it is difficult for me to say we are consdiering representing the KKK, if we let that first amendment protection be eroded, all of us will suffer for it."

Harley Hanson, whose wife filed the application, said today's KKK is different from the quasi-terrorist outfit responsible for the majority of the civil rights-era violence directed at blacks. "We can't change what happened, but we can still work for a better tomorrow," Hanson said.

The ACLU's decision to take the KKK's case seriously may feel jarring, but the group has a history of defending organizations whose views are apparently anathema to civil society.

In 1977, a neo-Nazi group announced its intention to march through Skokie, Illinois, a town in which one out of every six Jewish citizens was either Holocaust a survivor or was directly related to one. The ACLU took the case and successfully defended the Nazis' right to free speech. ACLU attorney David Goldberger found himself in the position of being a Jew defending the rights of Nazis to march against fellow Jews.

The KKK insists its application to adopt the Georgia highway was not a stunt. Hanson said the aim was to beautify the roadway, not to seek publicity.

Hardly anyone is buying it. Mark Potok, senior fellow at the Southern Poverty Law Center, said: "This is merely the latest iteration in an attempt by the modern Klan to portray itself as a kinder gentler organization as opposed to some terrorist outfit.

"It's a ploy. It's a publicity stunt. They don't intend to pick up a single beer bottle."

History of gimmicks

The KKK has a long history of attention-getting gimmicks. In a case that went to the supreme court in 2005, the KKK successfully won the right to adopt a stretch of Interstate 55 in Missouri. The state lost the case on the grounds that participation in the program cannot be denied because of a group's political beliefs.

A crafty state legislator, however, proposed a bill to have the portion of the highway that the Missouri KKK adopted renamed the Rosa Parks Highway. The name remains today, even as the Klan's sponsorship of the road has expired.

The only case where a Klan's petition to adopt a highway has been successfully blocked in the courts was in Vidor, Texas, according to Potok. In 1997 a court ruled that the petition for the sign was a deliberate attempt at intimidating residents of recently desegregated public housing, directly across the street.

Also in 1997 the Missouri chapter of the Klan attempted to underwrite the public radio program All Things Considered. For subsidizing a portion of the University of Missouri at St Louis's KWMU programming, the organization wanted the following message to be read in acknowledgment:

The Knights of the Ku Klux Klan, a White Christian organization, standing up for rights and values of White Christian America since 1865. For more information, please contact the Knights of the Ku Klux Klan, at P.O. Box 525, Imperial, Missouri, 63052. Let your voice be heard!

The 8th circuit court of appeals ruled in favor of the university, which argued that the message would drive potential students and alumni funding away.

"The Klan today is seen rightly as the author of the vast majority of the real violence of the civil rights movement," said Potok.

The Ku Klux Klan was formed in 1865 at the close of the Civil War and from the very beginning was synonymous with racially-motivated violence: lynchings, tar-and-featherings, rapes and other atrocities.

By 1925 its numbers had ballooned to 4 million, at a time when the entire population of the US was little more than 100 million, said Potok. It was a single, unitary Klan with headquarters in Georgia.

Its penchant for publicity stunts stretches back to at least the 1950s when it audaciously released staged photographs of Klansmen delivering Thanksgiving turkeys to poor black families.

The group was later responsible for the worst acts of violence against blacks during the civil rights movement, including the infamous bombing at the 16th Street Baptist Church in Birmingham, Alabama, which killed four young girls in 1963.

By the 1970s, after a string of hard-won civil rights legislative victories, the Klan's marginalization was well under way.

Today, according to the Southern Poverty Law Center, there are fewer than 6,000 members of the Klan. It is unlikely to lose the adopt-a-highway case in Georgia if it goes to court, said Potok. But it will be a toothless victory.

"The Klan today is a very, very small portion of the radical right," said Potok. "In fact, it is regarded by the rest of the radical right as incredibly lame. They are viewed as undereducated country bumpkins."