A recall is necessary when either a vehicle or various items in the vehicle do not comply with the safety standards set forth by the federal government.  Thus, when there is a safety related defect on the vehicle or in the equipment, a recall is necessary.  The federal government through the Federal Motor Vehicle Safety Standards has set minimum performance requirements for those aspects of an automobile which affect the safe operation such as brakes, lighting and tires or that provide protection for the operators and the riders in these automobiles from serious injury, death or permanent injury. 

Such an example would be air bags, safety belts, child restraints, energy-absorbing seats, steering columns and motorcycle helmets.  The standards set forth by the federal government apply to all vehicles.

According to the government, a safety related defect is one of which the performance of a motor vehicle or motor vehicle equipment is in a way that protects the public against unreasonable risk of accidents occurring because of the design, construction or performance of the motor vehicle and there is an unreasonable risk of death or injury in an accident involving that automobile or system.  Therefore, in short, there is a defect which poses a risk to motor vehicle safety and this may exist in some type of group of cars of the significantly similar design or same design and manufacturer.