Forbes: https://www.forbes.com/sites/eriksherman/2016/03/23/nixons-d...
CNN: https://www.cnn.com/2016/03/23/politics/john-ehrlichman-rich...
The Independent: https://www.independent.co.uk/news/world/americas/richard-ni...
Channel4: https://www.channel4.com/news/factcheck/factcheck-war-drugs-...
These were all in the first page of Google results with the query 'John Ehrlichman quote drug law'.