Green light is designation for a product certification that the product
- has not caused harm (by pollution, depletion of resources, etc.) to any fragile ecology in the region it was made;
- was not made with sweatshop labour (forced labour, child labour);
- revenues for which will not pay for corporate crimes.
It is also possible for a conditional endorsement to be made. This is a score easily translated into a price premium. If the price minus that price premium (which represents higher price you are willing to pay for the merits) is less than that of the alternative product, then you should buy it. But this means the same as a yellow light if the price is so close that premium is not obvious. In this case no single product can be green-lighted, but all alternatives to the top choices can probably be red lighted!
It is of course completely up to the consumer to choose the people or NGOs who are choosing which things to evaluate and how ie. what values should be given to the variables used in the calculation of the green light, yellow light and red light