NEW YORK (JTA) — The American Civil Liberties Union called on U.S. senators to oppose a measure targeting boycotts of Israel and its settlements.

The Israel Anti-Boycott Act, introduced in March by Sens. Ben Cardin, D-Md., and Rob Portman, R-Ohio, would expand 1970s-era laws that make illegal compliance with boycotts of Israel sponsored by governments — laws inspired at the time by the Arab League boycott of Israel — to include boycotts backed by international organizations. Those adhering to boycotts would be the subject of fines.

While the measure is aimed at the Boycott, Divestment and Sanctions movement, it also targets efforts by the United Nations and the European Union to distinguish products manufactured in Israel from those manufactured in West Bank settlements.

In a letter Monday, the ACLU urged senators not to co-sponsor the measure and to oppose its passage.

“We take no position for or against the effort to boycott Israel or any foreign country, for that matter,” wrote Faiz Shakir, ACLU’s national political director. “However, we do assert that the government cannot, consistent with the First Amendment, punish U.S. persons based solely on their expressed political beliefs.” Shakir added that “the bill would punish businesses and individuals based solely on their point of view. Such a penalty is in direct violation of the First Amendment.”

The measure was drafted with the assistance of the American Israel Public Affairs Committee and has the support of Christians United for Israel. It has 42 co-sponsors from both parties. A similar bill has gained 230 co-sponsors in the House of Representatives.

Liberal pro-Israel groups have objected in recent years to similar legislation, arguing that boycotting settlements — an action that some liberal Zionists support — should not be wrapped into broader boycotts of Israel, which most of the Jewish community rejects.