The Supreme Court’s recent term ended with a bit of a thud. Unlike years past, the court failed to issue any bombshell opinions on hot-button social or political issues. Shorthanded due to Justice Scalia’s death and the delay surrounding the appointment of his successor, the court proceeded with caution by reviewing cases of a technical nature and issuing tempered, rather narrow decisions in those cases.

This measured approach appears likely to change. The court has agreed to hear several high-profile cases, including the challenge to the Trump Administration’s travel ban. Indeed, most signs suggest the court is poised be more aggressive in the upcoming term — and more conservative — with Justice Neil Gorsuch now in place. But, if this past term is any indication, the court’s “conservative wing” is not as rock solid as some might think. Along with Justice Anthony Kennedy, a longtime swing vote, Chief Justice John Roberts displayed a willingness to join the Court’s left flank last term. Lee v. United States is a prime example.

As a teenager, Jae Lee moved from South Korea to the United States with his parents. He spent the next 35 years in the U.S. as a lawful permanent resident. Not once during that time did he visit South Korea. Lee became a successful restauranteur, but caught the attention of federal authorities after an informant reported that Lee had sold him drugs.

A police search uncovered drugs, money and a weapon. Lee acknowledged the drugs belonged to him. After he was indicted on drug charges, his lawyers started plea negotiations. Lee had one goal in mind throughout that process — to avoid deportation — and repeatedly asked his lawyer about the immigration consequences of various plea deals. His attorney ultimately assured Lee he would not be deported if he accepted a particular plea offer. Lee accepted it, only to learn later that his attorney was wrong. He had pleaded guilty to a felony that carried with it mandatory deportation after completing his prison term.

During post-conviction proceedings, Lee claimed he had received “ineffective assistance of counsel” in violation of the Constitution. According to Supreme Court case law, a lawyer is ineffective if he or she performed deficiently and that deficiency “prejudiced” the defendant. Prejudice in this context is tricky. In general, deficient lawyering prejudiced a defendant if it affected the outcome — if the defendant would have done better if the lawyer had not made the mistake. Defendants often struggle to satisfy the prejudice prong, especially in cases where the proof of guilt is overwhelming.

The government conceded that Lee had received subpar legal advice, but dug in its heels on the prejudice prong. Prosecutors insisted the deficient performance had not harmed Lee because he had such little chance of success at trial that, if he had declined the plea, he would have undoubtedly earned a harsher sentence and been deported in any event after he had served that sentence.

The Supreme Court ruled 6-2 in Lee’s favor. (Gorsuch sat this one out.) Roberts, in writing for the majority, emphasized the importance of Lee’s own decision-making process. “Common sense (not to mention our precedent) recognizes that there is more to consider than simply the likelihood of success at trial,” he wrote. “Here Lee alleges that avoiding deportation was the determinative factor for him; deportation after some time in prison was not meaningfully different from deportation after somewhat less time. He says he accordingly would have rejected any plea leading to deportation — even if it shaved off prison time — in favor of throwing a ‘Hail Mary’ at trial.”

How significant is this decision? On the hand, it can be interpreted as a defense-friendly case that reinforces the value of adequate legal representation at the plea stage. Traditionally, the Court has taken an “objective” approach to the prejudice prong when it comes to plea bargaining, looking at what a hypothetical, rational defendant would have done and whether the lawyer’s bad work affected that choice. Under this objective test, it can be quite difficult for defendants to show prejudice.

In Lee, however, the chief justice embraces a more “subjective” position, asking “what an individual defendant would have done” and accounting for the specific defendant’s unique decision-making process. This shift seems to have startled Justice Clarence Thomas, who wrote a strident dissent in Lee (joined by Justice Samuel Alito) that warned the holding would have “pernicious consequences” by emboldening defendants to challenge their plea agreements and thereby undermining the finality of those deals. On the other hand, Roberts emphasized “the unusual circumstances of this case,” particularly the prominence of deportation in Lee’s decision-making calculus. That means Lee might prove to be a somewhat idiosyncratic case that sheds little light on the Court’s future direction.

Even so, Lee should not be dismissed too quickly. It sends a powerful message to defense attorneys about the need to perform effectively during plea bargaining. And, perhaps more importantly, it reflects — and not for the first time (Exhibit A: Health Care) — Robert’s capacity to break from the conservative camp on occasion and chart his own course.