Jdifabio is correct. It's a pre-flight risk assessment. It is company specific as to how it is formulated and what constitutes too high of a risk. The pilot must perform a risk assessment before he accepts a request for a flight. If the risk is too high, then there is usually a requirement for a supervisor to approve the flight, and if it's too high for that, then the pilot can not take the flight.
The FAA mandates that all EMS Helicopters have some form of risk assessment but it must include: Static factors, Dynamic factors, and Mitigation strategies.
Static factors generally do not change throughout the day and can usually be determined first thing of the day: How long the pilot has been with the company, how many hours of flight time he has, How well does he know the route of flight
Dynamic factors can change from flight to flight: What is the current temperature/dewpoint spread, is icing forecasted, is it snowing, or thunderstorms.
Mitigation examples: Aircraft is equipped with Autopilot, landing area has been scoped out beforehand, landing at an airport, adding more fuel etc...