Bond, represented by experienced Supreme Court litigator and former Solicitor General Paul D. Clement, argued that the treaty power does not expand the limited and enumerated powers of Congress established under the Constitution. This same argument was made in a prior Supreme Court case, Medellin v. Texas, by Republican Sen. Ted Cruz when he was solicitor general of Texas.

This principle did not sit well with Justice Sonia Sotomayor, who aggressively defended the government’s position in favor of an expansive reading of federal authority. She claimed it would be “deeply ironic” if the Supreme Court invalidated the Chemical Weapons Convention Implementation Act just as we are trying to deal with Syria. But Bond is not challenging the validity of the treaty itself; she is challenging the authority of Congress to pass a federal law that usurps the traditional police power of the states. It is difficult to imagine that a refusal to uphold the prosecution of a woman in a domestic dispute could have any effect on the international dispute with Syria over weapons of mass destruction, a point made by Paul Clement.

The justices repeatedly questioned Solicitor General Verrilli about whether there are any constitutional limits on the power of Congress to enter treaties or implement them. Chief Justice Roberts specifically asked whether Congress could ratify a treaty that gave the federal government national police powers and then pass an implementing statute giving the federal government “the authority to prosecute purely local crimes.” Verrilli attempted to dodge the question by answering that it “seems unimaginable” that the Senate would ratify such a treaty, to which Justice Anthony Kennedy responded that it also “seems unimaginable that you would bring this prosecution.” The courtroom broke into laughter.

Ultimately, Verrilli’s answers on what limits there are on the government’s power under a treaty were confusing and contradictory. He specifically referred to the Senate’s ratification as “an important protection,” but then avoided giving an answer as to what the “outer bound” would be. Verrilli made it appear that the government does not really believe there is any limit.

In a bad sign for the government’s case, Justice Stephen Breyer repeatedly challenged Verrilli. The justice seemed genuinely irritated not only at his refusal to draw a line that defines how far the government’s power could extend under the Treaty Clause of the Constitution, but at his contention that the judiciary should have no role in construing the scope of domestic authority a particular treaty gives the federal government.

Breyer also appeared irked when Verrilli claimed that national security and foreign policy issues militated against the Supreme Court interfering in this area. The justice said that was the first he had heard of such a concern adding that he wondered why, if this was such a serious issue, the State Department had not filed a brief.

Breyer gave examples of prior cases that could have been prosecuted under the chemical weapons convention to illustrate how open-ended the treaty is given the government’s position. One featured a racehorse that was killed by a poisoned potato. All of Breyer’s examples involved chemicals even though they have “absolutely nothing to do with chemical weapons.” When Verrilli said those were just hypotheticals, not real cases, Breyer responded that these were real cases. Verrilli tried to fight back, saying that giving “vinegar to a goldfish” is not a real case. At that point, Justice Samuel Alito interjected that they were “not real cases because you haven’t prosecuted them yet.” The courtroom broke into laughter again.

The “vinegar to a goldfish” example was something that Justice Alito had raised in the oral argument during the Court’s first hearing of the Bond case. Under the government’s interpretation, Alito had said, it could prosecute an individual for using vinegar to kill a goldfish since the Chemical Weapons Convention bans the use of toxic chemicals to kill animals, too. On Tuesday, Alito was at it again, telling Verrilli:

A few days ago my wife and I distributed toxic chemicals to a great number of children. On Halloween we gave them chocolate bars. Chocolate is poison to dogs, so it’s a toxic chemical under the chemical weapons treaty.

Justice Breyer added that there was “chocolate all over the place,” and Justice Antonin Scalia commented that he “didn’t know horses ate potatoes,” leading to more laughter in the courtroom. When Verrilli, who seemed disconcerted by these comments, responded that “this was serious business,” Justice Alito pointed out:

If you told ordinary people that you are going to prosecute Ms. Bond for using a chemical weapon, they would be flabbergasted. It’s so far outside of the ordinary meaning of the word.

Justice Breyer was obviously concerned about the government’s definition of a chemical weapon:

We can tell joke after joke, but it’s not a joke that it’s so easy to make up examples that seem to have nothing to do with the problem of chemical weapons like the Syrian problem.

Breyer aptly summarized the concerns seemingly shared by many of the justices when he stated:

In principle [the government’s] position constitutionally would allow the President and the Senate, not the House, to do anything through a treaty that is not specifically within the prohibitions of the rights protections of the Constitution. … And I doubt that in that document the Framers intended to allow the President and the Senate to do anything. … Now if you carry it to an extreme, that’s what you are, that’s where you are, and I’m worried about that and I think others are, too.

A constitutional system of limited government cannot have a “loophole” through which the federal government can get unlimited authority. The treaty power of Article II is no such loophole.