A ban was the forbidding of a person, object, or action from being or happening.
Attempts to ban whaling on Earth in the 20th century hadn't stopped countries and pirates from killing whales. (Star Trek IV: The Voyage Home)
Creating mimetic simbiots was banned by the Lyssarian Prime Conclave. (ENT: "Similitude")
Stavos Keniclius was banned from his community for his plans to make a master race from clones, considered an anti-humanistic concept. (TAS: "The Infinite Vulcan")
The Federation banned the Varon-T disruptor. (TNG: "The Most Toys")
A training accident led to Starfleet Academy banning the Kolvoord Starburst maneuver. (TNG: "The First Duty")
Doing business with Quark was at one point banned by the Ferengi Commerce Authority. (DS9: "Business as Usual", "Ferengi Love Songs")
The Khitomer Accords banned subspace weapons. (Star Trek: Insurrection)