Ad idem
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Template:Cleanup-date As is often the case with lawyers in the United States, they bandy about Latin phrases without any real understanding as to what the Latin words mean, and without any regard as to the phrase's ultimate legitimacy, and regardless of whether the meaning that is arrived at, can be applied to the concept at hand. A single misspelling or misuse can creep into the attorney's argot, century by century, if not year by year, and for want of a classical education in Hebrew, Greek, and Latin, which gives the better attorneys a fitter grounding in the law, fails to find itself ever corrected.
"Ad idem" is a very frequent misspelling of the Latin words ad diem meaning "on a particular day" or "up to the aforementioned day" or "until a particular day" and, if used as an adjective, could even mean "up to date." The reason that lawyers miss this phrase, or misemploy it, is not just because they use spellchecking programs incapable of examining the matters more deeply, but because idem is a legitimate adverb in Latin, and the Norman Invasion that turned the legal world on its head introduced numerous instances of compound conjunctions into the legal language of the time. Thus, the Latin idem (meaning the same) could be compounded with the preposition ad to produce a pair of words employed as a single word, and without anything else to go on, the listener would be at a disadvantage trying to figure out what the lawyer had just said.
If the words AD IDEM are actually spelled that way, and are not in fact a misspelling, then it means "to the same" - as in a last will and testament devising real estate to a specific individual whose identity was painstakingly identified, or if not identified, will be ascertained in short order. AD IDEM, in this sense, has the same sense as AD IPSUM. For instance, if a man has devised property to a particular John of Blackacre, and a whole paragraph is devoted to the description of this individual, that he not be confused with anyone else, then a reference to this same person (the antecedent decedent) could be allowed again with a single reference, "AD IDEM" - to the same one - and the will would continue on from there.
Another possibility is that AD IDEM is a misspelling for AD ITEM, again as before a pair of words constituting a "compound construction" - in this case, a preposition and an adverb, something that probably entered into the legal language of lawyers through and subsequent to the Norman Invasion. AD ITEM means "to the point as well" or "to the same conclusion" or "to him also." AD ITEM is, in turn, a frequent misspelling of ad litem as in the phrase "custos ad litem" - (serving as) a guardian for the duration of the trial.
