## Core Concept
In a civil negligence case against a doctor, the fundamental principle revolves around the concept of **onus of proof** or the burden of proof. This concept is crucial in determining liability and involves establishing that the healthcare provider deviated from the standard of care expected in the medical community, and that this deviation directly caused harm to the patient.

## Why the Correct Answer is Right
The correct answer, **plaintiff (or patient)**, is based on the principle that in civil cases, including medical negligence, the burden of proof lies with the party that makes the claim—in this case, the patient or their representative. The plaintiff must provide sufficient evidence to support their claim that the doctor was negligent. This involves demonstrating that the doctor owed a duty of care, that there was a breach of that duty (i.e., the standard of care was not met), and that this breach caused harm or damage to the patient.

## Why Each Wrong Option is Incorrect
- **Option A: Defendant (doctor)** - This option is incorrect because, in civil cases, it is not the defendant's responsibility to prove their innocence; rather, it is the plaintiff's responsibility to prove the defendant's guilt or, in this context, negligence.
- **Option B: Medical Council** - This option is incorrect because, while medical councils or professional medical bodies may have a role in regulating medical practice and can be involved in proceedings to provide expert opinion on standards of care, they do not bear the onus of proof in a civil negligence case.
- **Option C: Court** - This option is incorrect because, although the court ultimately decides the case based on the evidence presented, it does not bear the onus of proof. The court's role is to evaluate the evidence provided by both parties.

## Clinical Pearl / High-Yield Fact
A crucial point to remember is that in cases of **medical negligence**, the standard of proof required is generally **'more probable than not'** or **'balance of probabilities'**. This means that the patient (plaintiff) must show that it is more likely than not that the doctor's negligence caused their injury. This standard is lower than that required in criminal cases but still necessitates thorough documentation and expert testimony.

## Correct Answer: D. plaintiff (or patient)