Cipher Pol is a series of World Government organizations, primarily used for tasks such as, assassinations and other underground work.
The various Cipher Pol cells are stationed throughout the world and investigate for the World Government. They supplement the Intelligence Branch of the World Government's Marine forces, but seem to operate more as a counter-insurgency agency that also has more general law enforcement duties. If they encounter pirates, they will apprehend them, but, as an agency, Cipher Pol seems to focus more on political threats to the World Government than more generic criminals. So far, the CP agencies seen on the Red Sea are CP5, CP6, CP7, CP9 and CP-0.
There are eight official Cipher Pols that are numbered from CP1 to CP8 with two unofficial units, which are named CP9 and CP-0. Cipher Pol No. 9 has the license to kill any citizen that does not cooperate with the World Government or acts in contrary its the interests. Because such a radical method of applying justice by the World Government should not be common knowledge, this group is a top secret organization. CP-0 is apparently more powerful than the CP9 as they are called the world's strongest intelligence.