IJ litigation isn’t only about abstract principles of constitutional law, although legal theory is an indispensable part of what we do. We must also provide real-world evidence that convinces courts that we should win. Of course, we present testimony from our own clients, and we cross-examine representatives of the government body that violated their rights. We present lots of documents. But one of the lesser-known parts of litigating a case is using expert witnesses effectively.

Experts play a variety of roles in IJ cases. We sometimes use experts just to give the landscape of an area. Most judges do not know how the funeral industry works, for example, or what eyebrow threading is. In these situations, experts educate the judge about the backdrop of the case so that the rest of the evidence makes sense.

Having someone who can accurately and effectively synthesize information from large numbers of documents can also be extremely useful. Often, we receive thousands of documents from the government, and we need to present evidence about what those documents say. We cannot expect that a judge will go through boxes of paperwork and painstakingly track data; instead, we have an expert do that. For example, in a property rights case challenging a city’s demand that renters submit to warrantless searches—much like our case in Orange City, Iowa, described here—we engaged an expert to go through hundreds of home inspection reports and see if those inspections actually turned up conditions that were genuine health or safety problems. (The answer? No.)

Experts can also speak from their knowledge of an area. In a lawsuit over a ban on the sale of homemade baked goods, for instance, an expert food microbiologist testified that he had never seen a report of someone getting sick from a homemade cookie. In one of our hair braiding cases, our expert testified about the fact that the cosmetology curriculum the state required braiders to complete did not teach braiding. She showed that by pointing to pictures of her own work in the standard cosmetology textbook and noting that the textbook incorrectly explained the techniques used. 

Other times, getting to the information at the heart of a case requires experts to do an experiment. In a food truck case, for example, an expert studied foot traffic patterns near both restaurants and food trucks to see if food trucks blocked sidewalks, as our opponents claimed. (The answer? No.) In our lawsuit against Albuquerque’s civil forfeiture program, our expert determined that the program was completely self-funding, meaning that employees’ salaries and jobs depended on the city taking enough money. 

Yet another way that experts help us is by reading the report of a competing expert and letting us know the best questions to ask at deposition. In one challenge to outrageous property code fines, our expert advised us to ask questions about standard municipal accounting practices to see if they were followed. (The answer? No.) We then showed the court that the city’s dependence on fines also differed from standard financial practice, giving the court just one more reason to strike down the city’s abusive policies.

With the help of expert witnesses and many other types of evidence, we show courts that financial incentives infect local government fining and forfeiture practices and that claims about the benefits of regulations that stifle entrepreneurship are completely false. Again and again, we combine strong evidence with convincing legal arguments and constitutional principles to make the world a freer place.

Dana Berliner is IJ’s senior vice president and litigation director.