Use the Book Reference, Rather than Supra
Don’t make your readers look back in your paper to piece together a complete citation. Your goal should be to keep your readers’ eyes moving forward and to make every citation as user-friendly as possible. Supra citations—such as Smith, supra at 222—send your readers scurrying back through your paper to find the original book reference. They stop your readers eyes from moving forward and interrupt the pace of your writing.
Don’t send your readers on a wild goose chase. Instead, repeat the book reference and say Smith, 400 F.2d at 222. If your readers are likely to know the name of the case, skip the name and simply say 400 F.2d at 222.
Use Id. Citations—But Not Too Many
Even though id. citations may require your readers to look back in the paper, id. citations are less troublesome than supra citations. Because id. citations refer to the immediately preceding citation, your readers do not have to wander far to complete the citation. And id. citations are so short that they are rarely disruptive. So, even though you should substitute the book reference for supra citations, you can leave your id. citations alone.
But use id. citations as an editing signal. Id. citations at the end of two or more consecutive sentences usually mean the sentences can be combined.
So make life easy for your readers. Don’t send them hunting for basic citation information.