It has always been my understanding that it is illegal to trade on MATERIAL NON PUBLIC information. Where there is a direct link to a company insider the guilt is obvious, however their can be instances where their is no direct link and guilt can't be so easily determined. It is therfore up to the SEC and the Courts to decide what MATERIAL NON PUBLIC information is.
The laws are intended to help those that are not on the inside but actually they hurt market participants who do not see all information reflected in market prices.
In the three cases you cited I personally would not trade on any because I belive they all constitute MATERIAL NON PUBLIC information. In reality I believe most insider trading cases are never discovered or prosecuted.