It is easy enough to understand how an act which results in harm can be defined as a crime.
But it is not as easy to understand how failing to act can also be defined as a criminal act. For a crime to be committed there is usually a requirement for an overt act (also called an actus reus) coupled with a specific intent to produce the resulting harm (also called mens rea). There are some crimes, however where criminal liability attaches when the accused failed to act.
The failure to act can only be a crime when the law in the first place required a duty for the accused to act. A parent is required by law to care for their child. Care for a child consists in the parent providing him with adequate food, promoting their good health, and ensuring that they are educated. If a parent neglects the child: does not give him adequate food, does not bring him to the hospital when he is sick and fails to send him to school, the parent is not complying with a statutory duty of caring for his child. His failure to act in compliance with the statutory duty exposes him to criminal liability for neglect.
When the law imposes a duty of care acting in a manner which is below the prescribed standard of care imposed by the law will also result in criminal liability. Conduct which increases risk of harm or injury also results in criminal negligence. A motorist who drives at high speed on a crowded highway and despite the traffic conditions, weaves through traffic is criminally liable for negligent driving even if no accident is caused by his manner of driving. His conduct increased the risk of harm or injury to himself as well as to other motorists on the road.
If this same motorist who weaves through traffic despite the congested condition of the highway, picks up speed, changes lanes abruptly and without using his turn signal he is criminally liable for reckless driving even if he does not cause any accident. His conduct shows not only negligence which is acting below the standard of care required by the law. His conduct shows recklessness. He increased the risk of harm or injury to himself and to other motorists and showed lack of regard for the safety of others on the road alongside him. This is a more serious degree of liability than mere simple negligence.
Disclaimer : This article is just a summary of the subject matter being discussed and should not be regarded as a comprehensive legal advice for you to defend yourself alone. If you are charged with criminal offences, it is recommended that you seek legal assistance from criminal lawyers.