Dr Butler specialises in government contracts, with a particular interest in defence procurement. In 2009, the EU adopted a controversial Defence and Security Procurement Directive, implemented in the UK Defence and Security Public Contracts Regulations 2011. These rules have had a significant impact on how Commercial Officers conduct procurement processes to achieve value for money for the UK taxpayer. Military officials also coming into acquisition roles from operational service are also having to adjust to detailed rules and work in conjunction with Commercial Officers to deliver vital defence capability to the front line.