On Wednesday, the human rights activist made his first-ever court appearance, in a case drawing attention to the issue at the core of the Israeli-Palestinian conflict: the battle for Jerusalem.
Ascherman, head of the local group Rabbis for Human Rights, went on trial along with two Israeli activists for blocking Israeli bulldozers from demolishing Palestinian homes built without permits.
Ascherman didn't deny blocking the bulldozers, instead arguing he had a moral responsibility to stop them.
"Our defense is basically that because the policy is illegal and immoral, that it's a civic, Jewish and Zionist duty to stand in front of the bulldozers," he said.
Control over Jerusalem — home to Jewish, Christian and Muslim holy sites — is the most contentious issue between Israel and the Palestinians.
Israel claims the entire city as its eternal capital. The Palestinians seek east Jerusalem, which Israel captured in the 1967 Mideast war, as capital of a future state.
Jerusalem's overall Jewish population was more than double the 221,900 Arabs at the end of 2002, according to the Jerusalem Institute for Israel Studies. But the Arab population is growing at a rate more than three times that of the Jewish population, the group says.
Faced with the grim demographic trend, Israel has built neighborhoods throughout east Jerusalem over the past three decades with the goal of fortifying its hold on the holy city.
Critics, including Ascherman, claim that Israel has also tried to prevent Palestinian growth in the city by creating bureaucratic obstacles.
Rabbis for Human Rights says Palestinian residents of Jerusalem rarely receive the necessary permits without paying bribes, a charge the municipality denies.
In the meantime, Israel demolishes some 40 Palestinian homes a year in east Jerusalem for not having proper paperwork, Ascherman said.
Ascherman was charged with blocking police from demolishing homes in east Jerusalem in two incidents last year. His co-defendants, Shai Eliezer Tzvi and Omer Ori, were charged with joining Ascherman in the second incident.
The municipality said demolitions occur only in cases of "especially flagrant" violations.
Ascherman, a Reform rabbi originally from Erie, Pa., said he has been involved in such issues for some two decades.
"From a teenager on, I felt that that the basis of what I wanted to do as a rabbi was to uphold ethical values," he said.
Most Jewish religious leaders in Israel are from the Orthodox stream, which in recent years has veered to the right and is widely associated with the nationalist side of Israeli politics.
But Ascherman said Judaism was essentially compassionate.
"The very core of Judaism is the teaching from the Bible that all human beings are created in God's image," he said. "Either that means that we respect the image of God, the humanity, the human rights of every human being. Or it means nothing. It means that we throw the Bible into the trash can."
If convicted, the three men could face fines, community service and up to three years in prison.
The case was continued until March.
