The case is Berg v. Kelly, decided on July 25. The claim is that the protesters were detained in the press pen in violation of the Fourth Amendment. The government argued that the "special needs" exception to the Fourth Amendment justified the detention. "Special needs" allows the police to conduct a limited search or temporary seizure that serves "special needs beyond the normal need for law enforcement." You don't see "special needs" arise that often, and the legal standard is difficult to articulate. The asserted special needs here was protecting the President. Case law "generally recognize[s] protection of the President as a special need apart from routine law enforcement," and the Second Circuit adopts that principle here. But the Court of Appeals (Hall, Raggi and Carney) says the government is not entitled to summary judgment in this case because the record says very little about the risk to Obama's safety during the demonstration if the protesters were allowed to go home in small groups and watch TV. So that claim survives.
But it really does not survive because the government wins the case on other grounds: qualified immunity. This form of immunity lets governmental defendants -- including the police -- off the hook when the case law was not crystal clear at the time that they were violating the Constitution. The police get immunity here because the government has a huge interest in presidential safety, and "an objectively reasonable officer could have thought that the temporary detention here offered a permissible method of serving the heightened security need that exists during a Presidential visit." Here is the crux of the reasoning:
Officers charged with the duty of protecting the President reasonably could have concluded that—where OWS protesters had left the unrestricted designated protest area and entered an area set aside not for them but for the press—a reasonable way to allow the protesters to pursue their protest without risk that they would attempt to get closer still to the President was to require them to remain in the press pen until the President departed the area. With the benefit of hindsight, other means might be imagined to safeguard the President while also allowing plaintiffs to protest with less restriction on their freedom of movement. But the officers were balancing a number of legitimate concerns, including consideration for First and Fourth Amendment rights, in a dynamic situation. At the time in question no clearly established law signaled that the Officers’ conduct fell outside the special needs doctrine.