'Tort' is French for 'error' or 'wrong.' American English borrowed the term, arguably, to allow a linguistic distinction between 'error' and 'a legally actionable error.' Tort and medical malpractice are used somewhat interchangeably in legal parlance. Both refer to a wrongful act effected in the course of a duty, which engenders liability. Where medicine is concerned, and where it crosses paths with civil personal injury litigation, it becomes crucial to ascertain what distinguishes an ‘error' and an ‘legally actionable error.' Many kinds of errors and adverse outcomes can occur in the course of medical treatment; not all of these errors are legally actionable, however. Lawmakers attempt to tightly define which kind of mistakes will give rise to liability with very specific language, thereby clarifying what constitutes medical malpractice and what does not.
Healthcare providers are liable for proven instances of malpractice. What exactly is an act "malpractice?" Are providers liable for simple cases of unavoidable human error? Harmless errors, but errors nevertheless? Are they liable for the inherent risks of a given procedure, or plausible, well-known complications? Flawless medical care that still ended in a bad result? Blatant recklessness? We will explore when and why these things are causes of liability, and when they are not.
Medical Malpractice: Deviation from Standard of Care
Beginning with the forthright definitions of negligence and malpractice. If Medical Malpractice were a 101 class, the first principle one would learn in this class is this: in order to file a medical malpractice claim, negligence must have occurred. A bad result alone is not grounds for a claim. The plaintiff must have proof that the provider acted negligently. There are many ways one could define negligence, for the purposes of medical liability. It could be construed as carelessness, or as a harmful error that would have been reasonably prevented with due diligence. Legally, negligence is shown by contrasting the negligent act against the standard of care in that medical field.
Duty, in tort law, is a legal obligation imposed on one individual which requires that they adhere to a standard of behavior in the course of actions where others could foreseeably be harmed. Healthcare providers have a legal duty to adhere to the standard of care within their field. If a plaintiff brings forth a claim of medical malpractice, they have the burden of proving that the act in question was negligent. If an act is harmful and negligent, it will necessarily deviate from the accepted standard of care. Thus, the plaintiff must provide expert testimony to establish the standard of care in that field and how it was breached. The plaintiff's attorney will present the argument that the defendant negligently departed from the standard of care, and that said departure proximately caused their injury. The causal relationship between the act of negligence and the injury must exist. If a provider negligently or carelessly departs from the standard of care they owed to the patient, but did not cause injury to the patient by doing so, there may be no grounds for a malpractice suit. Or, if they negligently deviated from the standard of care, and the patient was injured but for a different reason, then the provider likewise may not be found liable.
The best way to understand what malpractice is, is to examine what it isn't. By reviewing circumstances that do not give rise to malpractice claims, one may obtain a far better understanding of the definition of malpractice. We will further flesh out the meaning of negligence and what constitutes grounds for medical malpractice later on.
Medical care does not always give way to a good result, even if it was flawlessly executed exactly in accordance with the standard of care, and the healthcare provider did all that was expected of him or her. In such cases, if a patient's condition does not improve or worsens there is no actual legal basis to bring a claim against the provider. They adhered to the standard of care they owed the patient and therefore are not liable for tort. If they did negligently deviate from the standard of care, or the worsened condition was preventable, there may be grounds for a malpractice claim.
Disclosure of Medical Risks
Some procedures carry inherent risks and known complications. It is important to note that the provider has a responsibility to disclose all significant risks and complications to the patient before carrying out a procedure or treatment, and the patient must give written consent. If a provider obtains consent from the patient but fails to disclose the associated risks and complications, their consent might be considered invalid, however this alone would not actually be cause for liability. Only if one of those risks or complications comes to fruition, proximately harming the patient, does that failure of full disclosure become legally actionable.
The provider still erred in not disclosing the risks, but they are not liable if the patient is not harmed. If the patient is harmed, the patient's consent is not a credit to the provider because it was not informed consent. If the provider does disclose all risks to the patient and obtains informed written consent, they are not liable if a disclosed complication does occur. The patient was made aware of the risk, and knowingly still consented to the procedure - in this case there is no grounds for suit. The provider acted in accordance with the standard of care by informing the patient and obtaining their consent. In layman's terms, they have to tell you all risks and give you the option to say no. If you say yes, they must have it in writing. If they fail on any of these counts and you are injured, they could be liable. If they fail on any of these counts and you are not at all injured, there is probably no cause for liability.
This a convenient segway into the topic of 'harmless' error. Generally speaking, if a medical error was made but did not create or contribute to patient injury, it will probably not give rise to liability. A distinction may still be made between 'harmless errors' and 'errors that don't engender liability.' For example, an admitted error might've been harmful in some capacity, but if the plaintiff sues for an injury that was not a result of that particular error, then that error didn't engender liability. Or, as mentioned, an error might cause an injury which was entirely disclosed to the patient in accordance with informed consent laws, and thus isn't grounds for a malpractice claim.
A strange question arises when a provider becomes aware that they have made a medical error. Many providers fear disclosing an error to patients for liability reasons, however small or 'harmless.' Admitting fault or even expressing apology was a legal grey area in malpractice suits, until some states began including explicit ‘apology clauses' in malpractice law.  These clauses permitted doctors to express an apology without it becoming a source of liability, or being taken as an admission of guilt for malpractice. If a provider makes an error that is in fact harmful to the patient, they are generally required to disclose it and thus admit fault. But things get sticky when determining whether or not an error was harmful. Who is making that call?
The person who made the error, the person who stands to be sued if they disclose it. When the error is only privately known by whomever made it - the question of whether it was harmful is up to their sole discretion. They have a vested interest in what call to make, and it could certainly sway their decision. Furthermore, what is initially deemed a “harmless” error could be harmful later on. The JAMA Network reports that there are as many as 1 million annual medical errors, an estimated 50% to 96% of which go unreported. Denoting an example of the situation discussed above, the article in JAMA reads "A physician's decision to disclose may be based on the perception whether an event actually constitutes an error and the degree of harm incurred. Physicians are often poor at predicting future medical outcomes. At the time a potential error occurs, a surgeon is often not in the position to say unequivocally whether the event will result in a subsequent adverse clinical event or whether there will be long-term significant harm.” 
Choosing not to disclose a harmless error is arguably more of an ethical failing than a legal/actionable failing. Not to mention, patients cannot sue for mistakes that they never knew about and which had no adverse and detectable effect on their wellbeing. Does the figure suggesting 1 million annual errors, albeit speculative, bespeak a greater failing on the part of the healthcare industry? It is difficult to ascertain because some amount of human error cannot be avoided, but 1 million annual errors is perhaps too high to constitute a rate of 'normal human error.' A statistic that some might find shocking: medical errors are the third leading cause of death in the United States, falling just after heart disease and cancer, and just before respiratory disease.  This includes every manner of medical error, from negligent recklessness to errors initially thought to be "harmless."
Examples of Medical Negligence
To better understand the meaning of ‘negligence,' let's review some examples.
A doctor has access to your medical records and/or had a previous patient-provider relationship with you. You are allergic to a certain drug and this is clearly stated in your medical records. The doctor prescribes you this drug regardless because they carelessly did not consult your medical records. You become ill from ingesting the drug. You may be able to sue the doctor for malpractice because consulting your medical records for conditions like a drug allergy is a facet of the standard of care they legally owed you.
You enter a hospital with a great deal of intense neck pain and an inability to move your head. You undergo routine blood testing, which shows an unusually high white blood cell count. Informed only by these findings, the physician who sees you hastily gives a diagnosis of shingles. No other tests are performed and you are released, but your pain persists. Several days later, you check into a different hospital with worsened symptoms, including bilateral weakness and impaired speech. Physicians at this hospital perform CT scans, quickly uncovering ruptured and herniated discs, an epidural hematoma, and an abscess causing compression of the spinal chord. Had the first physician performed these routine tests, they reasonably would have discovered these maladies as well. Due to a hasty and incorrect diagnosis and a failure to perform tests that are routine under the circumstances, your illness went undetected - written off as shingles for several more days during which your condition significantly worsened. Arguably, those several wasted days closed the window of opportunity for doctors to operate and obtain a more favorable outcome. By the time you are operated on, the damage is too great and you have suffered a significant injury. You may bring a malpractice suit against the physician who misdiagnosed you and further deviated from the standard of care by failing to perform CT scans under those circumstances.
The difference between medical errors and malpractice is nuanced and at times, fairly confusing. Malpractice is always is based on some demonstrable medical error, but not all medical errors constitute malpractice. The term ‘medical error' encompasses a vast range of situations of varying severity, only some of which are legally actionable. A medical error may harmless and never disclosed. It may be an unavoidable instance of human error and very harmful. It may be the result of gross carelessness. It may deviate from the standard of care but not proximately cause injury to a patient. This is just a sampling of the variety of situations that can arise in this complex field.
 Morton, Heather. "Medical Professionals Apologies Statutes." Ncsl.org. National Conference of State Legislatures, 21 Jan. 2014. Web. 11 Apr. 2017. <http://www.ncsl.org/research/financial-services-and-commerce/medical-professional-apologies-statutes.aspx>.
 Chamberlain CJ, Koniaris LG, Wu AW, Pawlik TM. Disclosure of “Nonharmful” Medical Errors and Other EventsDuty to Disclose. Arch Surg. 2012;147(3):282-286. doi:10.1001/archsurg.2011.1005
 Makary Martin A, Daniel Michael. Medical error—the third leading cause of death in the US BMJ 2016; 353 :i2139