The first thing is the sheer amount of information. The standardized portion of the bar exam that nearly every jurisdiction uses, known as the MBE or multistate bar examination, covers more than a half-dozen subjects, some of them being the basis of year-long law school courses, all of them dealing with very complex and detailed information. These subjects include contracts, property law, torts, civil procedure, criminal law, evidence, and constitutional law. One example: Memorizing the various time periods involved in a civil action: 14 days for expiration of TRO, time to file jury demand after serving the last pleading directed to the jury triable issue, and time to appeal a class action certification or denial; 21 days to answer a complaint or to file a Rule 12 motion, to amend a pleading once, and to withdraw a pleading or motion after service of a Rule 11 motion; 28 days, time after judgment to file a renewed motion for judgment as a matter of law or to file a new trial motion; etc., etc., etc. Another example: knowing when the cutoffs are for various Rule 12(b) motions. Some can be filed any time but others must be filed before certain points in the litigation or you lose your right to assert them. An examinee has to know the subjects down to this level of detail for thousands of pages of material--and not just be able to parrot them, but to apply them during an analysis of comples fact patterns under extreme exam time pressure.
On top of this, each state requires this same depth of knowledge on an additional number of subjects--as many as a dozen, or perhaps more. These often include business associations, family law, wills and trusts, secured transactions, conflicts of law, and remedies. Finally, you are examinied on your ability to draft documents, make a persuasive argument, or analyze strengths and weaknesses of a hypothetical client's case.
The rule of thumb is that it takes about six hundred hours of intense work to prepare adequately for the bar exam (and this on top of three years of law school).
