Apple’s MFi (Made for iPhone) guidelines have been changed to encourage the production of cases that specifically target their device protection on falls from 1 meter onto hard surfaces – even if dropped screen-first.
Case manufacturers will need to rigorously test to make sure that such falls will not harm the iPhone wearing the case. Additionally, in order to protect the screen from damage, they will require a 1mm buffer between the iPhone’s screen and the surface its placed on, if it’s face-down. That, or they can cover the screen entirely.
Further than that, Apple has declared a number of materials considered environmentally hazardous or unfit for the MFi licence. Formaldehyde and a number of other chemicals are included on this list, and are generally materials that are already outlawed in the US and in Europe, but this ensures that no advantage can be gained from manufacturers outside these regions that use environmentally irresponsible materials.