CRIFS
Marty BergenMy former bridge partner, Marty Bergen, has 11 conventions named after him. Bergen Raises, Bergen over Notrump, BROMAD (Bergen Raise of Major After Double) and on and on ad nausea.
I would like just one "Cohen" convention and I will get to it at the end of this article.
Meanwhile, let's talk about 4th seat.
After Pass-Pass-Pass, there are some items to consider such as: FOURTH-SEAT WEAK 2-BIDS The normal range for a weak 2-bid is 6-10. But, after three passes, surely you wouldn't open the bidding with 6 points (nor 7, 8, or 9). Really, the range for a 4th-seat weak two should be about 10-14. After three passes, I'd be happy to open 2
with: K Q 10 9 6 5
K 3
9 8
K J 5
. This combines preemption with description. Of course, you can't open this hand 2 in any other seat, because it is too strong. Three-level preempts in fourth seat also show close to opening-bid values.
RULE of 15The "book" rule on whether or not to open with a 1-level bid in 4th seat says to add your HCP to your number of spades. If the total is 15, open the bidding. If less than 15, pass it out. The theory is that it will be a partscore battle, and if your side doesn't have enough of the high-ranking suit, you could easily lose the battle. So, you would pass out this hand:4
K J 5 4
K J 8 7
K 9 8 7
(11 HCP + 1 spade=12) but open: K Q 10 9 2
A J 4
8 7 6
5 3
(10 HCP + 5 spades=15). This rule is commonly called either "Pearson Points" or "Casino Count."
DRURYWhen you open in 4th seat, you are often on the light side. If you open 1 with K Q 10 9 2
A J 4
8 7 6
5 3, you don't want partner to get too excited. Say that he has a good hand with game interest (A J 5
7 6
J 4 2
A J 8 7 2).
You wouldn't want to get too high opposite that hand (8 tricks are the limit). The responder is too strong for 2, but rather than bid 3, he can bid an artificial 2 to say he has a limit raise (it is just a coincidence that this example contains a club suit--the Drury 2 bid says nothing about clubs). Playing modern Drury, the opener would then rebid 2 to say he is not interested in game and the partnership stops safely on the two level. (Technically, this is called "Reverse_Drury," but it is the way "everyone" plays it.) Drury is also used after 3rd-seat openings (also potentially light).
CRIFS
Meckwell
Now, forget the Rule of 15 for deciding whether to open or pass out the deal in fourth seat. I prefer CRIFS- "Cohen's Rule In Fourth Seat." Any time it is borderline (like 10, 11, 12 HCP), evaluate your opponents! Yes, I am serious. If you are playing against Jeff Meckstroth and Eric Rodwell (or the best pair at your local duplicate game), then pass it out. You will likely get a middlish score/result. Who needs to open and have to do battle with an expert pair who will fight hard for the partscore and play or defend well? Conversely, if you look up at your opponents and see Schlemiel and Schlimazel (the worst pair), then open the bidding. You can push them around in the auction and will get an extra trick or two in the play/defense. You rate to go plus--so don't pass the board out.
I ask just two small favors:
1) Please publicize this treatment with the "CRIFS" acronym.
2) Please don't tell your opponents why you opened that 10-count in fourth seat (I don't want them to know what we think of their game). 
