Who and When?
James M. Schlatter discovered Aspartame in 1965. James M. Schlatter discovered Aspartame accidentally while he was working for the company G.D. Searle & Company. He was a chemist and was working on the development of an antiulcer drug when he accidentally synthesized Aspartame. He discovered it's sweet taste when, without realizing that his finger was contaminated, licked it.
Aspartame after the discovery
Aspartame has been critically and commonly reviewed by the FDA due to speculation about Aspartame causing brain cancer and other health concerns. All of these health concerns have been dissmissed by the FDA because the affects (if any) of aspartame were very minor once evaluated. Currently there are no restrictions on the use of Aspartame due to any health issues.