Generally, a person owes everyone else with whom he or she comes in contact a general “duty of care.” Normally, you don’t have to worry about this duty – it is the same in all instances: the duty to behave with the care that would be shown by a reasonable person. But there are several situations in which courts hold that people owe one another less than this regular duty. The most important of these situations are: 1) one generally has no duty to take affirmative action to help another; and 2) one generally has no duty to avoid causing unintended mental suffering to another.
A person generally cannot be liable in tort solely on the grounds that he or she has failed to act. This means that if you see that another person is in danger, and you fail to render assistance (even though you could do so easily and safely), you are not liable for refusing to assist.
Example: Sam, passing by, sees Mike drowning in a pond. Sam could easily pull Mike to safety without risk to Sam, but instead, Sam walks on by. Sam is not liable to Mike for any harm sustained by Mike.
There are a number of commonly-recognized exceptions to the “no duty to act” rule. In the above example, if the danger or injury to Mike is due to Sam’s own conduct, or to an instrument under Sam’s control, Sam has the duty of assistance. Similarly, in the event Sam started to give Mike assistance, once Sam voluntarily begins to render assistance to Mike (even if he was under no legal obligation to do so), Sam must now proceed with reasonable care.