First published in Insider.

Bill Marler is an attorney who specializes in food borne illness cases.

Most of the cases he’s worked on have involved either undercooked or prepackaged foods.

He’s learned to always order food cooked well done and to avoid salads to reduce his risk of food poisoning.

When it comes to eating carefully in restaurants, Bill Marler is something of an expert.

The attorney has spent nearly three decades representing people who have experienced food borne illnesses caused by E. coli, Salmonella, and Listeria, among other pathogens.

Marler told Insider that he’s observed some common trends in what kinds of foods make people sick. In general, he said eating at home is the best way to minimize your risk of consuming undercooked or contaminated food.

“A lot of it has to do with being able to control your own environment: washing fruits and vegetables thoroughly, cooking the ones that need to be cooked,” Marler said.

But even Marler still dines out on occasion, although he joked that he’s not the most popular dinner party guest.

Here are a few rules that he’s followed to avoid poisoning for his entire career to date:

Salads are a bacterial minefield

Marler said of all the outbreaks he’s litigated on in recent decades, an overwhelming majority of them have led back to foods that were technically prewashed.

Outbreaks of E. coli linked to romaine lettuce and listeria tied to bagged salads are among some of the more well-known recent outbreaks. But what consumers might not realize is that they could be served a prepackaged salad in a restaurant.

“Even in the best restaurants, it’s usually pretty packaged salads that they use,” Marler told Insider. “They may or may not cut them up themselves and wash them themselves.”

Rather than ask every restaurant staff about their food preparation, Marler said he plays it safe and orders cooked vegetables instead. If he wants a salad, he’ll eat at home.

Most cases he’s worked on are linked to undercooked meat

Most instances where people get sick from eating in restaurants end up leading back to raw or undercooked foods, Marler told Insider.

Raw meat may contain bacteria such as salmonella or campylobacter — the most common culprits of food poisoning. These bacteria are destroyed when meat is cooked thoroughly.

After hearing enough horror stories from clients who were served undercooked meat, the lawyer now takes a cautious approach: if he’s ordering meat, it has to be well done.

“Sometimes chefs look at me a little askance when I’m ordering a well-done steak, but it’s part of my process,” Marler said.

Foodborne illnesses linked to shellfish are on the rise

When asked if he ever orders raw seafoods like oysters or sashimi in restaurants, Marler answered with an emphatic “no.”

Oysters are high on Marler’s list of foods that routinely get linked to food poisoning outbreaks. He previously told Insider that he’s seen an uptick in foodborne illnesses linked to shellfish in the past decade, in part due to warming waters.

Consuming raw shellfish is especially risky because they’re not cooked to kill off harmful viruses and bacteria.

Since mid-January 2022, more than 400 people have fallen ill in Canada and the United States after consuming raw oysters contaminated with norovirus, a highly contagious virus that causes diarrhea and vomiting.