After a car accident, a patient is brought to the Emergency…

After a car accident, a patient is brought to the Emergency Department. The client is alert and oriented, but states he has dyspnea. O2 sats fluctuate between 88% to 90%. O2 is applied at 2L per nasal cannula, with no improvement. O2 per mask is initiated, again with no improvement. Suddenly the client loses consciousness, has a respiratory arrest and subsequently dies. After the code is called, it is found that the O2 was never turned on by the nurse. What is the key ethical principle involved in this situation?