A prominent British National Party member could be struck from the teaching register if he is found to have espoused racial and religious intolerance.
Adam Walker and his brother Mark, both teachers in County Durham, admit posting criticisms of immigrants and Muslims from their school computers.
The men, who were both candidates for the right-wing party at last year's council elections, deny intolerance.
Adam Walker, 39, is appearing before England's General Teaching Council (GTC) - the first time a teacher has faced professional charges for religious intolerance. He resigned from Houghton Kepier Sports College after the school began disciplinary action.
His brother Mark, 37, has been suspended from his teaching job at Sunnydale College. He said BNP members were being "victimised" because of their political views.
Adam Walker is the president of Solidarity, a trade union closely associated with the BNP.
He claims the GTC chairwoman, Judy Moorhouse, a past president of the National Union of Teachers, is biased against him, and he is seeking to have her removed from the disciplinary hearing panel.
The case could be as incendiary as the 2006 race hate prosecution of Nick Griffin, the BNP leader who claimed his acquittal as a victory for freedom of speech. Adam Walker looks set to take a similar line. In a statement to The TES, he said the GTC case was driven by "politically motivated spite".
"No other teacher at the school has had their internet use monitored in the way mine was," he added. "My real `crime' is political dissidence."
The design teacher, a former soldier, has been working as a supply teacher for the past year.
Pat Harrington, Solidarity's general secretary, said Adam Walker had criticised asylum seekers, immigrants, Muslims and the promotion of homosexuality.
"He was very angry about things that were going on in the news," Mr Harrington said. "It was at the time when Ken Bigley was having his head chopped off, and when the policewoman was shot."
"The way he wrote was, I think, very intemperate, and he would now accept that he could have expressed his views better."
But he should not be seen as a racist, Mr Harrington said. He taught karate and had been married to a Japanese woman.
Ben Doherty, an employment solicitor with Pinsent Masons, said political comment might not give rise to an employment action.
"Provided you don't identify your employer and are not inciting racial hatred you could say whatever you want about race or religion issues," he said.
But Christina McAnea, of the Unison union, questioned whether BNP members should be allowed to teach. "Schools should be centres of learning and tolerance, not a breeding ground for the poisonous views of the BNP," she said.