The No Fly List and the Watch List are not necessarily accurate means of predicting whether a person is a mass shooter. For example, there have been numerous cases of innocent people being on the No Fly List. Yusuf Islam (Cat Stevens) was placed on the list, as was Ted Kennedy, and most ironically, Georgia Democrat Rep. John Lewis, who now ardently supports the No Fly List as the means to regulate gun ownership in the U.S.  The other problem with the No Fly List or Watch List as being a means to an end is that it replaces the mantra of "innocent until proven guilty" into the reverse, "guilty until proven innocent", which is not how our justice system should work. Finally, the Orlando shooter had been placed on a terrorism watch list, but his charges were dropped by the FBI because there was not enough evidence.