At Elizabeth Holmes Trial, Jurist Takes Middle Path

In the most closely watched trial of his career, Judge Davila, 69 years old, has given prosecutors enough leeway to make their case, while also at times appearing deferential to Ms. Holmes and her legal team, observers said. He has lent a sympathetic ear to nervous jurors and wished Ms. Holmes well upon learning she was pregnant.

For lawyers who know Judge Davila, his performance in the spotlight looks much like how he operates in the more routine fraud and drug cases that come before his court.

“He’s going to be super careful and give both sides a lot of latitude,” said Eduardo Roy, a criminal defense lawyer who has practiced in the judge’s court. ”He definitely has a lot of patience.”

The trial comes years after the downfall of Theranos, which at one point was valued at more than $9 billion on the promise that its finger-prick blood tests could revolutionize the healthcare industry. Prosecutors claim Ms. Holmes—once the world’s youngest self-made female billionaire—defrauded investors out of hundreds of millions of dollars.

Ms. Holmes’s lawyers have aggressively defended against the charges and say she did nothing wrong beyond running a failed business.

Over three years of legal wrangling before trial and seven weeks in court, Judge Davila has often split the difference between what each side is requesting.

In one such instance, the judge ruled that patients and doctors could testify about Theranos blood tests they believed to be inaccurate, but that the testimony couldn’t veer into any emotional impacts the tests had on them.

The ruling retained a key prong of the prosecution’s case, the voices of the alleged victims, but eliminated what could have been moments of high drama as patients testified about tests that incorrectly said they were miscarrying or HIV-positive.

Lawyers for Ms. Holmes had repeatedly asked the court to exclude the patient and doctor witnesses completely, saying they were merely anecdotal absent wider data on the accuracy of Theranos’s tests.

The decision was part of a 100-page pretrial ruling in May that also spelled out the judge’s reasoning in admitting text messages between Ms. Holmes and her ex-boyfriend into evidence and explaining why Ms. Holmes’s lawyers couldn’t blame investors for their losses.

In another split-the-difference decision from that ruling, Judge Davila said prosecutors could tell jurors broad-strokes details about the type of lifestyle that Ms. Holmes led while in charge of Theranos, but couldn’t give any examples of extravagances.

“He kept out some of the stuff from the government that was inflammatory, and gave the government plenty to make their case,” said Andrey Spektor, a former federal prosecutor in New York who isn’t involved with the Theranos trial but has tracked Judge Davila’s many decisions in the case. “It’s a very fair decision.”

Judge Davila had a working-class upbringing, growing up in a Spanish-speaking household in the 1960s in Mountain View, Calif., under the care of his mother, grandmother and aunt.

His legal career started as a public defender in Santa Clara County, which includes much of Silicon Valley. With a fellow public defender in 1988, he started a private law practice in San Jose.

In 2001, then-Gov. Gray Davis appointed him to the Santa Clara County Superior Court. His most high-profile case on that bench was a fraud prosecution of a different sort from the Theranos trial—the tabloid sensation known as the chili finger hoax. Judge Davila sentenced a Nevada couple to several years in prison after they were convicted on charges related to planting a severed finger in a bowl of Wendy’s chili in a scheme to extort the fast-food chain.

President Barack Obama nominated him to the federal bench in 2010, and the Senate confirmed him the following year.

Some judges run their courtrooms with a short temper and an iron hand. On the federal bench, Judge Davila has restrained himself in situations in which he was provoked, according to trial transcripts.

During jury selection in a drug-trafficking case in 2015, Judge Davila quizzed a salesman about the answers he filled out in his juror-qualification questionnaire. The man wrote that he believed Luke Skywalker to be his father and that he hates people and the show “Friends,” and listed his college major as “screw you,” according to the transcript.

Judge Davila told him he was disappointed. “I looked at that, sir, and it caused me to believe that perhaps you take light of this case and perhaps you take light of this court,” he said before dismissing him.

At sentencing, the judge has at times factored in personal hardships suffered by the defendants and called their misdeeds tragic failures of judgment.

Outside the courtroom, the judge’s interests are eclectic. Sam Polverino, the judge’s former law partner, described Judge Davila’s hobby of tinkering with classic cars as somewhere between a pastime and an obsession. Mr. Polverino said he owns a hulking 1940s Buick and a peppy little 1970s BMW and tinkers with them at a local auto repair space that he rents.

He said Judge Davila loves Beethoven and Gershwin, fountain pens and vintage Rolex watches, showing him once how to spot a fake.

“Ed’s blessed with a human touch,” Mr. Polverino said. “That’s what distinguishes him.”

When Ms. Holmes told the court she was pregnant earlier this year, delaying the trial, Judge Davila didn’t match the annoyance expressed by prosecutors that they weren’t told about the pregnancy sooner. Instead, he said he would do anything necessary to accommodate Ms. Holmes’s needs after giving birth, including setting aside a private room in the courthouse for her to use.

During the last hearing before she gave birth, Judge Davila didn’t address the pregnancy directly, but concluded the proceeding by saying, “Let me just extend our best wishes to everyone in future endeavors. We hope the best.”

—Heather Somerville contributed to this article.

Write to Jacob Gershman at [email protected] and Sara Randazzo at [email protected]