Deacons pub in Christchurch Road has been shut down by police who suspect it was being used by drug dealers.
Dorset Police obtained a temporary closure notice against the premises which is thought to be connected with the "use, production or supply of class A drugs".
The pub temporarily closed in February following the death of a customer.
The Home Office introduced new laws on Monday which extend current crack house closure powers under the Criminal Justice and Immigration Act 2008.
Home Secretary Jacqui Smith said: "The new premise closure order power will enable police forces and local authorities to close any premises - privately owned or rented accommodation - that cause significant and persistent disorder in the local community. That means no-one will be able to hide from the law if they cause serious nuisance to their neighbours.
"Premises closures will only be used as a last resort, but they make it clear that anyone who thinks they can flout the law and get away with it is just plain wrong."