Halbig opinion on DC Circuit website, other materials in law school repository
Update (Nov. 7,’14): Prof. Adler’s own post on Volock (following the U.S. Supreme Court grant of cert. in the case) references these two compilations of reference material posted by his co-author, Michael Cannon:
The opinion of the 3-judge panel is here.
The article is available on Scholarly Commons, the law school’s repository of scholarship: http://scholarlycommons.law.case.edu/faculty_publications/25/
EDITED TO ADD:
And the 4th Circuit has just released its ruling in the parallel King v. Burwell. All three judges on this panel upheld the subsidies, with one also writing a concurring opinion.