Classification or advisory opinions are usually issued by the Office of General Counsel. The opinions indicate whether such games should be classified as Class II or Class III as defined in the IGRA and NIGC regulations. Opinions that have already been determined are indexed below:

• Advisory opinions are not final agency actions
• Bingo, games similar to Bingo, and Class III Bingo implementations
• Card Games
• Class II Games
• Class III Games
• Games of Chance
• Grandfathered Games 
• Internet gaming 
• Instant Scratch Off Games
• Non-gambling games 
• Other games 
• Pull Tabs and Class III Pull Tabs implementations