L. J. O’Toole, “Research on Policy Implementation: Assessment and Prospects,” Journal of Public Administration Research and Theory, vol. 10, no. 2, pp. 263–288, Apr. 2000, doi: 10.1093/oxfordjournals.jpart.a024270. 

Policy implementation is broadly defined as “what happens between the establishment of an apparent intention on the part of the government to do something, or to stop doing something, and the ultimate impact in the world of action”