Q:

How is it possible for this circuit to continue functioning correctly?

A circuit uses the RN5RT33A voltage regulator to generate the 3.3V rail.
According to its datasheet the abs. max output current is 150mA, typical output current is 60mA.
There's an add-on board that feeds on that 3.3V rail and draws additional current from the regulator. I've measured the approx. current used by the add-on board and it was why of 310mA max and around 200mA most of the time.
How is that possible? It seems that would exceed the ratings of the regulator, however the circuit seems to be working fine. 

A:

The value given in the datasheet as "absolute maximum" is the maximum value at which the manufacturer guarantees the device will not break. That doesn't mean it will break, just that it may break and if it does it's definitely your fault, so they're not legally liable for damages caused.
Most of the time, devices can survive conditions outside their absolute maximum, as long as they aren't too far outside it and don't stay outside it for too long. But you shouldn't depend on that, and you definitely shouldn't depend on them actually doing what they're meant to do under those conditions.

