There is debate in these countries about whether such cards and their centralised database constitute an infringement of privacy and civil liberties. Most criticism is directed towards the enhanced possibilities of extensive abuse of centralised and comprehensive databases storing sensitive data. A 2006 survey of UK Open University students concluded that the planned compulsory identity card under the Identity Cards Act 2006 coupled with a central government database generated the most negative response among several alternative configurations. None of the countries listed above mandate possession of identity documents, but they have de facto equivalents since these countries still require proof of identity in many situations. For example, all vehicle drivers must have a driving licence, and young people may need to use specially issued "proof of age cards" when purchasing alcohol. In addition, and uniquely among native English-speaking countries without ID cards, the United States requires all its male residents between the ages of 18 and 25, including foreigners, to register for military conscription.