What Is Anchoring Bias and How Can It Undermine Expert Witness Work?

When people ask me what it’s like working as an Aesthetic Expert Witness, they often assume it’s just about knowing your stuff and writing it down. But that’s really only part of the picture. Being a good expert isn’t just about having clinical knowledge, you also need to think independently, examining every detail with fresh eyes, and not allowing someone else’s opinion to steer your own.

A recent case from the High Court, Skykomish Ltd v Gerald Eve LLP, caught my attention for exactly that reason. It wasn’t about aesthetic medicine, it was actually a property dispute, but it highlighted something I think all expert witnesses, regardless of field, need to be always aware of: anchoring bias.

The Case

The case involved a valuation expert brought in late, after two previous experts from the same firm had already withdrawn. Time was short and the pressure was obviously high, and rather than building her own view from scratch, the expert leaned too heavily on the work of her predecessors. The judge pointed this out in his ruling, calling attention to the way her opinion seemed “anchored” to the previous experts’ assessments. The problem is that she hadn’t broken free of the work that came before her, unfortunately costing her credibility in court.

The principle is simple: when you're asked to provide expert evidence, your job is to assess the facts and come to your own conclusions.

Anchoring Bias

Anchoring bias is something psychologists have been studying for many years. It’s our tendency to rely too heavily on the first piece of information we’re given, even if it’s not reliable. Once an idea gets lodged in your mind - a diagnosis, a number, a treatment plan, or someone else’s opinion - it becomes harder to detach from it. That’s fine when you’re choosing dinner or guessing someone’s age, but when you're giving evidence in court, it can be dangerous.

In aesthetics, where many expert witness cases involve serious complications from cosmetic treatments, anchoring can creep in more easily than we think. Sometimes there’s already a detailed medical report prepared by the clinic involved, and you might be tempted to read what's already there and use it as a starting point. But we must approach each case like it’s the first time anyone has looked at it.

What does that mean?

That means reviewing every clinical photo, every consent form, every set of notes and messages. Taking the time to understand what happened, what should have happened, and how the patient was affected. It means never assuming, and not letting your thoughts drift toward someone else’s version of events. That independence is every expert witness’ duty. If a judge or jury is going to rely on my opinion to make a legal decision, I need to be absolutely sure it’s based on my own reasoning and experience. 

This case also raised another important point: time. The expert in question had very little of it. She was brought in late, given complex material to work through, and expected to deliver an opinion quickly. It’s no surprise that mistakes were made. We should always make clear how much time we will need to review the case thoroughly and not rush it.

If you’re reading this as a lawyer, a fellow expert witness, or even a patient, I’d leave you with this: expert opinions carry real weight. Make sure the ones you rely on are built from scratch.