A federal rule banning fake online reviews is now in effect.

The Federal Trade Commission issued the rulein August banning the sale or purchase of online reviews. The rule, which went into effect Monday, allows the agency to seek civil penalties against those who knowingly violate it.

“Fake reviews not only waste people’s time and money, but also pollute the marketplace and divert business away from honest competitors,” FTC Chair Lina Khan said about the rule in August. She added that the rule will “protect Americans from getting cheated, put businesses that unlawfully game the system on notice, and promote markets that are fair, honest, and competitive.”