The contracts received a lot of negative press because some employers included 'exclusivity clauses'. This prevented workers working for anyone else even when they were not being given any work by the employer. In May 2015 the Government brought in new regulations governing the use of zero hours contracts which prevented exclusivity clauses from being used.
The BIS guidance guide explains to employers how zero-hour contracts work, the difference between appropriate and inappropriate use of such arrangements, and gives guidance on best practice and alternatives to zero-hour contracts. The full guide can be accessed here.