Patent examination has the one-hand rule.
The rule, as I've heard it stated, says that if a claim is longer than the length of the examiner's hand, it's allowable. I've heard it more than once, from more than one examiner. The thing is, it's a complete fallacy. I know of not a single examiner, not even the ones from whom I've heard it, who actually subscribe to it.
Of course, as with any 'rule of thumb', there is a grain of truth to it. If the applicant has added that many limitations to a claim (usually I'd assume only done by a pro se applicant, or an attorney who has been through many rounds of rejections), it's definitely going to catch an examiner's attention. With so many claim limitations for which to find prior art, it's only natural to think that there's probably something in there that would make the claim allowable. Besides that, there's the (completely justified) belief that if you need to combine an excessive number of references to reject a claim (examiners differ among themselves as to what constitutes 'excessive', as of course do attorneys), the rejection is in all probability so weak as to render it impotent. Better not to make such a rejection in the first place.
But let's take a step back and think about this situation. What good are claims with lots of limitations to an applicant? Such claims are so narrowed as to make them, to my mind, virtually worthless. (I'm talking here about claims of really excessive length, perhaps a page and a half or more.) So why present them at all? If the applicant is prosecuting the application pro se, the answer is obvious. However, if an attorney presents such claims, the question remains.
Well, perhaps instead of being indicative of allowability, maybe an excessive number of limitations is exactly the opposite -- an indication that the applicant/attorney is making a desperate attempt to try to get something allowed when there's really nothing there. Maybe claims containing a great many limitations are nothing more than an attempt to simply overwhelm the examiner into allowing the claims. In reality, the rule of thumb could be that the longer the claim (past a certain point), the less likely it is to be allowable.
If there is some particular aspect of an invention that renders it patent-worthy, you would think (or at least I would) that an applicant and/or attorney would be able to bring out the novel aspects of the invention without throwing everything but the kitchen sink into the independent claim.
I've had it happen to me once that I remember. An attorney filed an RCE, and canceled all of the 30-some claims except for a few independent claims, into which they incorporated all of the dependent limitations. The remaining independent claims were roughly analogous, and were each about two pages long. The thing was, though, that they had failed to incorporate anything new; all they did was incorporate existing limitations. Sure, the claims were long, and they included a whole lot of limitations, but they were the same limitations that I'd already previously rejected. In that case, the attorney made it easy on me. All I had to do to was to combine the rejections that I'd already written.
I imagine that if I'd seen the claims in that form before I'd performed the initial search, I'd have been fairly dismayed, and not at all optimistic that I'd be able to find art anticipating all of the limitations in any reasonable amount of time. It certainly seems much easier to search claims when the limitations appear in the nice bite-sized chunks that we're all used to seeing.
I must admit, until I sat down and really thought about this kind of claim (that is, until I wrote this post), it never occurred to me that excessively long claims might deserve more scrutinization than shorter claims. As I said, I've only seen them myself the one time, so I've never really had to think about it. But the next time I see them, you can be sure I'll be taking a close look at those claims.