One of the problems with cartels is the extent to which members cheat. According to the EIA, OPEC’s members can be expected to cheat on their latest agreement to cut production though, oddly, EIA expects them to cheat less than usual:

A key question regarding OPEC’s October 24 announcement of a 1.5 million bbl/d output cut is how much of the announced reduction actually will be implemented now and in the coming months. All OPEC producers except Saudi Arabia have recently been producing at, or close to, capacity. EIA’s current working view is that the actual OPEC cut between October and January could reach 1.1 million bbl/d. This represents about 70 percent of the announced cut, compared to a typical 50 percent compliance rate with previous OPEC cuts. While compliance with past announced cuts has often decreased over time, current market conditions and an expected growth in non-OPEC production may help maintain discipline among OPEC members and keep OPEC crude production from rising in 2009.