Intervention in Markets - Will the legal highs ban work?

Thanks to the BBC for this
http://www.tutor2u.net/economics/blog/intervention-in-markets-will-the-legal-highs-ban-work?utm_medium=email&utm_campaign=Economics%20daily%20digest%20Wed%201st%20June%202016&utm_content=Economics%20daily%20digest%20Wed%201st%20June%202016+CID_37bfd5fa8e4755e9117bafbff6018fca&utm_source=CampMonitor&utm_term=Intervention%20in%20Markets%20-%20Will%20the%20legal%20highs%20ban%20work%20A%20ban%20on%20the%20sale%20of%20legal%20highs%20has%20come%20into%20force%20in%20England%20But%20will%20be%20ban%20be%20effective%20Or%20does%20it%20risk%20creating%20even%20greater%20harm