The decision says that a detainee's counsel is entitled to review all classified information that is helpful to his defense, and in the case of habeas proceedings all information that is necessary to facilitate a habeas review. Such information is what the court considers "material", and it is up to the court review the information in camera to determine whether classified information meets that standard. Here's a list of things the court found to be material:
- Exculpatory evidence
- Inculpatory evidence relating to sources such as: source bias, coercion of the source, or inconsistent information from the source.
- Information containing names of witnesses that may have useful information.
This decision gives some more definition as to how review of all the pending habeas cases will go. Furthermore, I think it is a step in the direction of defining what kinds of procedures the U.S. will use in the future to handle national security cases.