The trial of Conrad Murray, the doctor caring for pop star Michael Jackson when he died of respiratory failure, begs the question: When does poor medical practice become criminal?

This week, Murray faces a California jury on involuntary manslaughter charges. Murray allegedly gave Jackson dangerous doses of a powerful anesthetic called propofol to help the King of Pop sleep. If convicted, Murray could serve up to four years behind bars as well as lose his medical license.

NEWS: Vaccine-Autism Doctor Accused of 'Deliberate Fraud'

At the heart of medicine and at the heart of this case lies the idea of "standard of care" -- that doctors should act responsibly and cautiously to avoid harming patients. In the United States, states have their own codes to determine what constitutes malpractice.

Medical malpractice usually results in civil cases. Doctors are sued for everything from leaving surgical tools inside a patient to making a bad diagnosis. Surgeons may face wrongful death charges in civil court from a patient's family.

Here, compensation -- not jail time -- is what's at stake.

Manslaughter, or the unlawful killing of a human being without malice, must involve behavior that grossly breaches standard of care. Despite each state holding its own definition of manslaughter, the type of negligence to justify this charge is in a ballpark of its own, one California attorney told Discovery News.

"He or she [the doctor] acts in such a way that is such a deviation from standard of care that it almost takes your breath away," said Julie Cantor, a practicing attorney with a medical degree and adjunct professor at the UCLA School of Law. "It's a gross incompetence or indifference to a patient's well-being."

Because lawyers believe Murray did not intend to kill Jackson, the doctor could not be charged with murder or voluntary manslaughter -- both of which require varying levels of intentionality or forethought.

SCIENCE CHANNEL: Puzzles: Medical Oddities

But Murray's actions were negligent enough to warrant involuntary manslaughter charges, experts say. For the accusation to hold, prosecutors must prove criminal negligence, or that the doctor put himself in a position that other doctors would not have.

Administering propofol outside of a hospital without proper training, using the drug to treat insomnia rather than as an anesthetic, failing to use proper technology to monitor Jackson and not calling for help immediately when his patient stopped breathing are the kinds of evidence that would all pile up against Murray.

Since he faces criminal charges, prosecutors must provide convincing evidence to the jury that Murray's actions were far removed from how others would have acted in his position. Even then, cases are rarely brought unless there's a good chance jurors will side with the prosecution.

Concepts of blame also underlie malpractice and criminal accusations. A person can be considered blameless if he experiences an unfortunate, adverse event that can happen to anybody. Because medicine involves making quick decisions in uncertain conditions, doctors don't always get the results they set out for.

In instances when the action is defensible -- if someone else in the same situation might have done it -- medical mistakes usually end up at civil courts in the form of malpractice charges. On the other hand, a person is blameworthy when he acts recklessly by ignoring information that endangers the patient. Showing up to work intoxicated, sexually abusing patients or pursuing illegal behaviors while on the job are blameworthy, too.

"District attorneys have discretion and they can bring cases for certain reasons and decide not to bring cases for certain reasons," Cantor said.

One high profile case in the early 1990s involved Nelson Yamamoto, a Los Angeles County sheriff who died at the hospital from gun wounds. After his death, the state launched an investigation into his medical care, but involuntary manslaughter charges weren't pursued because state legal experts understood that "juries are reluctant to send physicians to jail for mistakes made in good faith, not matter how grievous those mistakes are," Cantor said.

NEWS: Michael Jackson's 'Thriller' Jacket Sells

Murray's trial is receiving overwhelming national attention, but there have been more extreme cases where doctors were convicted of murder. Michael Swango, a physician, plead guilty in 1998 to killing patients and co-workers, and Milos Klvana was convicted of second-degree murder of newborns in California nearly a decade ago.

Still, charging doctors with manslaughter is rare, said Charles Bosk, a professor of sociology and medical ethics at the University of Pennsylvania. Instead, accusations often stem from political and social stances.

"There are occasional tendencies to criminalize physicians' behavior around certain issues such as late stage abortion and over-prescribing opiates," Bosk said.

When it comes to pointing fingers, though, there are other parties to consider in Murray's case. Murray's legal team also uses this idea in his defense, claiming that other health professionals bear responsibility in providing Jackson with a range of medications.

"Murray himself could not have done what he did without the collaboration, facilitation and looking the other way of a whole lot of other people," Bosk said. "That doesn't mean he's blameless, because I think he's probably not, but he's not the only one."