Proving Your Case – Causation

Proving Causation Medical Negligence in Illinois

Proving Your Case – Causation – To establish a case for medical malpractice, the plaintiff must prove that the defendant had a duty to the plaintiff, that the defendant failed to meet the standard of care owed to the plaintiff, that the mistake actually caused the plaintiffs injury and that the doctor or other medical professional’s negligence damaged the plaintiff.

What is causation in medical negligence?: “Causation” in medical negligence cases means proving that negligence as a result of a breached duty of care has caused injury. Proving this is known as “establishing causation”.

Proving causation in Illinois can be a difficult issue in a medical malpractice case. For one thing, the injuries generally involved in medical malpractice cases require specific medical training to understand, and the normal plaintiff may not know the cause of such injuries. It is important to contact an experienced medical malpractice attorney at Patel & Lehman, PC in Champaign – Urbana, Danville, Illinois, who can evaluate your situation and work with experts to prove medical causation.

Preponderance of the Evidence

How to Prove Causation?: In medical malpractice cases, the burden is on the plaintiff to establish, by a preponderance of the evidence, that the defendant was the cause of the plaintiffs injury. This simply means that the plaintiff must prove that it was more likely than not that the defendant’s actions caused the plaintiffs injury. This may be especially hard to do in cases where the plaintiff alleges that the injury is one that might ordinarily be the expected result of the original disease or condition; that is, where the plaintiff is basically alleging a failure to cure.

Types of Causation (Actual Cause vs Proximate Cause)

There are two types of causation: Actual Cause (cause-in-fact) and Proximate Cause. The defendant’s actions are the cause-in-fact of the plaintiffs injury if the plaintiff would not have been injured “but for” the defendant’s wrongful act, or if the plaintiffs injury was a foreseeable result of the defendant’s action.

Proximate cause deals with the issue of whether, considering all other relevant factors, the defendant’s actions were the legal cause of the plaintiffs injury. “Establishing a link between malpractice and harm is Proximate causation.”

The defendant will often try to demonstrate that there are other causes for the plaintiffs injury. One such possible cause is the plaintiffs pre-existing condition, that is, the plaintiffs original illness or injury for which he or she sought medical treatment. In addition, the defendant may try to show that the plaintiff was negligent in some way, and that this negligence, and not the health care provider’s, actually caused the plaintiff’s injury.

The health care provider may also argue that even if he or she deviated from acceptable medical procedures, such a deviation would not have altered the outcome for the plaintiff. Further, the health care provider might argue that there was a “superseding cause” or “intervening cause” that serves to shift liability to another third party who caused a new, independent, and unforeseen harm.

Expert Testimony – Proving Causation In A Medical Malpractice Case

Because of the complexity of the subject matter of medical malpractice cases, it is generally held that the plaintiff must rely on expert testimony to support causation. Most medical issues are not within the common knowledge of the plaintiff or the jury, so an expert’s testimony can help the jury understand the applicable standard of care, whether the defendant provider failed to meet that standard, causation and damages. Medical malpractice cases often come down to a “battle of the experts” between the plaintiffs expert and the defendant’s expert, who each offer opinions on the plaintiffs underlying condition, defendant’s actions, whether they were in line with the standard of care and whether the defendant caused the plaintiffs injuries. In some cases, such as where the result of the medical treatment or surgery is so obvious that a layperson can understand it, an expert may not be necessary.

Res Ipsa Loquitur

If a patient is injured as the result of a medical procedure but does not know exactly what caused his or her injury, but it is an injury that would not have occurred without negligence by a health care provider, the plaintiff might be able to invoke the legal doctrine known as “res ipsa loquitur.” This is a Latin phrase that means “the thing speaks for itself,” and implies that the plaintiff needs to show only that a particular result occurred, and it would not have happened but for the defendant’s negligence. A classic example of the type of case in which res ipsa loquitur arises is one in which a medical instrument is left inside a person following surgery. Clearly, an instrument would not be left inside a person in the absence of someone’s negligence.

To successfully invoke res ipsa loquitur, the plaintiff must show that:

  • There is no evidence of the actual cause of the injury
  • The injury is not the kind that ordinarily occurs in the absence of negligence
  • The plaintiff was not responsible for his or her own injury
  • The defendant, or its employees or agents, had exclusive control over the instrumentality that caused the injury
  • The injury could not have been caused by any instrumentality other than that over which the defendant had control


Issues of medical causation can be some of the most difficult issues to prove in a medical malpractice case. Because of this, expert testimony is often required. An experienced medical malpractice lawyer at Patel Law, PC can gather the necessary documentation and medical records and work with experts to build a case for proving causation in medical malpractice.