In a Rolling Stone article published on August 21, Professor David Cohen responded to President Trump’s statement that “sheriffs” and other “law enforcement” would be stationed at polling places in November to prevent voter fraud.

“Rest assured, he can’t do this,” writes Cohen. A federal law, 18 U.S. Code § 592.Troops at polls, prohibits the President from stationing military and non-military law enforcement, including FBI agents, U.S. attorneys, etc., at polling places. According to Cohen, the only exception to this law is if a police presence is necessary “to repel armed enemies of the United States,” a circumstance that Trump hasn’t claimed to be of concern in November’s election.

President Trump is also prohibited from stationing state law enforcement, such as sheriffs, at polling places under a 1997 Supreme Court decision. The decision holds that the federal government cannot compel local law enforcement to implement federal law—the underlying reasoning being that local law enforcement only work for their state government.

Cohen concludes that there is little action President Trump can legally take to realize his statement.