A bipartisan group of lawmakers, led by Senators Ben Cardin (D-MD) and Rob Portman (R-OH), is quietly working to criminalize the boycotting of Israel.

The bill, appropriately titled the Israel Anti-Boycott Act, establishes criminal and civil penalties of up to $1 million for American persons and companies who engage in actions “which have the effect of furthering or supporting . . . restrictive trade practices or boycotts fostered or imposed by any international governmental organization against Israel.” While it’s unclear how strictly the act would be enforced, it is clearly a gross infringement on free speech — targeting Americans who choose to exercise their First Amendment rights and engage in an organized boycott.

The Senate measure was conceived after the United Nations Human Rights Council voted in 2016 to create a “blacklist” of companies that do business in Israeli settlements in the West Bank and East Jerusalem. Building on a 1979 law designed to counteract the Arab League’s boycott of Israel, the Cardin-Portman legislation would extend the existing prohibition to cover boycotts against Israel called for by international organizations like the United Nations and the European Union.

The legislation, which currently enjoys the support of fifty senators, both Democrats and Republicans, faces uncertain prospects in the new Congress, where Democrats will control the House and new members, like Rashida Tlaib (D-MI) and Ilhan Omar (D-MN), have publicly endorsed the Boycott, Divestment, Sanctions movement (BDS). Senators like Bernie Sanders and, more surprisingly, Dianne Feinstein have also pushed back against the Cardin-Portman bill, and a lawsuit filed by Bahia Amawi — a Palestinian-American who recently lost her job at a Texas elementary school for refusing to sign a “pro-Israel loyalty oath” — has provided additional ammunition.

But whether the bill passes or not, it is part of an ominous trend to curb Palestinian grassroots activism and silence political speech critical of Israel. “Since 2014,” the advocacy group Palestine Legal reports, “at least 102 anti-BDS measures have been introduced in state/local legislatures across the country. As of November 2018, 26 states have enacted anti-BDS laws.” The law that ensnared Amawi mandated that she promise that she wouldn’t boycott or “otherwise tak[e] any action that is intended to inflict economic harm” on Israel.

Boycotting goods is a longstanding American tradition. The American Colonists refused to buy imported British manufacturers to protest excessive taxes. Abolitionists and antislavery activists swore off slave labor–produced products in favor of “free goods.” The New York Manumission Society organized boycotts against New York merchants and newspaper owners involved in the slave trade.

The tradition carried over into the twentieth century. In March 1933, the Jewish War Veterans of America staged a mass rally in New York City, where congressman William W. Cohen told those gathered that “any Jew buying one penny’s worth of merchandise made in Germany is a traitor to his people.” Civil rights activists staged boycotts of segregated buses and streetcars in the South in the middle of the century. Antiwar activists boycotted US defense contractors during the Vietnam War and published detailed lists of military contracts held by GE and other companies. The anti-apartheid movement refused to purchase South African wines and oranges, declined to compete with all-white Olympics teams, and shamed US businesses that profited from the racist system.

The fundamental principle guiding these activists was that boycotting goods to protest injustice was not only a civil right, but also a civic duty.

Today, Americans acting in solidarity with Palestinians are doing the same thing: boycotting goods from Israeli settlements to pressure the country to end its decades-long occupation and expansionist policies. Rooting themselves in previous struggles, boycotters compare Israel’s oppressive policies to those of apartheid South Africa. Many cite Israel’s separation barrier, which runs deep into Palestinian lands, displacing Palestinian communities and cutting off their towns and villages from one another. Others point to Israel’s two-tiered system in the West Bank, which provides preferential treatment to Israeli settlers while imposing harsh restrictions on Palestinians.

American advocates for Palestinian rights also draw inspiration from the legacy of the Civil Rights Movement. Ahed Tamimi, the West Bank teenager who was jailed for defying occupation and shoving a heavily armed Israeli soldier, has been hailed as “the Palestinian Rosa Parks.” Bahia Amawi is now competing for a similar title.

Like their American counterparts, Palestinian activists see nonviolent resistance, including the use of boycotts, as the best path to justice and freedom. The idea is not to “single out Israel for punishment,” as Israel’s advocates insist, but to remind them that occupation and segregation and apartheid bear a price.

Americans have a civil right to boycott Israel, both as a matter of conscience and as means of pressuring it to change its unjust policies. It’s a right both enshrined in the constitution and rooted in the country’s dissident political tradition. To deny this right is to threaten to turn the clock back to the days of McCarthyite repression.