Democratic senators are thinking twice about the proposed Israel Anti-Boycott Act after an outcry by the American Civil Liberties Union (ACLU), which considers it a “serious threat to free speech.”

While Maryland Sen. Ben Cardin, the bill’s lead author, said that the ACLU had misinterpreted the piece of legislation, he expressed his intention to “make it clearer.”

The act targets the boycott, divestment, and sanctions movement, an international effort to boycott businesses in Israel and occupied Palestinian territories in order to pressure Israel to comply with international law and stop the further construction of settlements.

The bill would threaten large fines and prison time for businesses and individuals who don’t buy from Israeli companies operating in occupied Palestinian territories, and who make statements, including social media posts, saying that they are doing so in order to boycott.

A central question at issue is whether the law’s violators would be punished by a felony conviction and up to $1 million and 20 years in prison, as the ACLU’s analysis shows. Cardin said that the legislation’s authors only intended to apply civil penalties, and that they were “willing to deal with these issues.”