Hundreds of law professors from schools across the country published an open letter Friday declaring President Donald Trump’s conduct involving Ukraine as “clearly impeachable,” an assertion that comes after a daylong hearing earlier this week at which Republicans and Democrats sharply divided over their assessment of the president’s actions.

The letter, posted on the website Medium and sponsored by the government watchdog Protect Democracy, had been signed by 520 professors as of Friday afternoon. The assertions were an attempt to frame the debate as one of law, and not partisan politics.