The practice was never an official punishment in the United States, but rather a form of vigilante justice. It was eventually abandoned as society moved away from public, corporal punishment and toward rehabilitation of criminals.
First degree burns are sustained after a split second contact with a material that is about 70 °C (160 °F). The same is also sustained after thirty seconds of contact with 55 °C (130 °F) material. The tar of that period was of such a quality that it only melted at about 60 °C (140 °F) but was often heated to higher temperatures. At temperatures of 60 °C (140 °F) burns can be created with a three second contact.
Furthermore, after the tar had cooled, it and the feathers would have to be peeled or rubbed off with lard, usually taking a good deal of skin with them. These would leave ugly scars and infection could set in. Depending on how "complete" the job was done, there was also a risk of heat stroke as the tar would act as a strong insulator and prevent the skin from breathing.
As a public or vigilante punishment, the purpose is to socially ostracize the victim. The hot tar scars and disfigures so the victim would be seen, wherever he went, to have suffered the punishment. The feathers serve to dehumanize the victim and expulsion from the community by carting or running him out of town completes the act. Riding a rail (especially the old sharp-edged triangular style) could cut and damage the crotch and impair the victim's ability to walk without pain. The agonized screams of the victim were typically drowned out by the noise of the crowd and the clanging of metal objects (pans, bells, etc.).
A later instance of this penalty being inflicted is given in Notes and Queries (series 4, vol. v), which quotes one James Howell writing from Madrid, in 1623, of the "boisterous Bishop of Halberstadt," who, "having taken a place where there were two monasteries of nuns and friars, he caused divers feather beds to be ripped, and all the feathers thrown into a great hall, whither the nuns and friars were thrust naked with their bodies oiled and pitched and to tumble among these feathers, which makes them here (Madrid) presage him an ill-death." In 1696 a London bailiff, who attempted to serve process on a debtor who had taken refuge within the precincts of the Savoy, was tarred and feathered and taken in a wheelbarrow to the Strand, where he was tied to the maypole which stood by what is now Somerset House, as an improvised pillory.
The first recorded incident in America was in 1766: Captain William Smith was tarred, feathered, and dumped into the harbor of Norfolk, Virginia, by a mob that included the town's Mayor. He was picked up by a vessel just as his strength was giving out. He survived, and was later quoted as saying that "...[they] dawbed my body and face all over with tar and afterwards threw feathers on me." As with most other tar-and-feathers victims in the following decade, Smith was suspected of informing on smugglers to the British Customs service.
The punishment appeared in Salem, Massachusetts, in 1767, when mobs avenged themselves on low-level employees of the Customs service with tar and feathers. In October 1769, a mob in Boston attacked a Customs service sailor the same way, and a few similar attacks followed through 1774 (the tarring and feathering of customs worker John Malcolm received particular attention in 1774). Such acts associated the punishment with the Patriot side of the American Revolution. In March 1775, a British regiment inflicted the same treatment on a Massachusetts man they suspected of trying to buy their muskets. There is no case of a person dying from being tarred and feathered in this period.
During the Whiskey Rebellion, the punishment was inflicted on Federal tax agents by local farmers.
In the early years of the Latter Day Saint movement during the early-to-mid 1800s, many of its adherents were tarred and feathered as a way to pressure the early LDS into leaving town or renouncing their beliefs.
In 1851 a Know-Nothing mob in Ellsworth, Maine tarred and feathered a Swiss-born Jesuit priest, Father John Bapst, in the midst of a local controversy over religious education in grammar schools. Bapst fled Ellsworth to settle in nearby Bangor, Maine, where there was a large Irish-Catholic community, and a local high school there is named for him. Catholic Encyclopedia
Also during the 19th and 20th centuries, many African Americans were subjected to this treatment as a form of punishment or harassment.
Following the Liberation of France in World War II there were instances of alleged German collaborators being tarred and feathered by street mobs. Most of the victims of this practice were women accused of a Collaboration horizontale, i.e., sexual relations with German soldiers.
Similar tactics were also used by the Provisional Irish Republican Army (IRA) during the early years of the The Troubles. Many of the victims were women who had been in sexual relationships with policemen or British soldiers.
There was a report of a swindler being tarred, feathered, and ridden on a rail near Pigeon Forge, TN, in the 1990s. In addition to six weeks in hospital, he spent three years in prison for his crimes. His attackers were never identified.
In August 2007, loyalist groups in Northern Ireland were linked to the tarring and feathering of an individual accused of drug-dealing.