Ok, fare enough.
It is assumed to drive predefined current to the R_load, while the value of the current is set by a corresponding voltage on the Ref pin. The purpose of the instrumentation amplifier (to the right) with the sensing resistor R_sns is to convert current to voltage and to provide the negative feedback to the OpAmp (to the left).
The higher the voltage output on the OpAmp the higher the current through R_sns, then the higher the voltage output on the Instr.Amp and, hence, the higher the input voltage on the negative input of the OpAmp. Thus, providing a proper feedback. Shouldn't this be the case or I'm missing something?