There also seems to be one other aspect to the Somali pirates scenario that many are missing...
Most governments are too "Civilized" to retaliate against a given "Government" when clearly that government is:
A) incapable of clearing out the pirates themselves
B) incapable of identifying the pirates as pirates (and external governments aren't either
C) clearly not supporting the pirates
As a consequence of all that - none of those world class navies are willing to step in, enforce embargoes against the offending nation(s), nor engage in hostilities against Somalia as they might have against a nation that is clearly supporting the acts which would be construed as acts of war by a competent nation.
As for myself? I have no issue with having pirates in my campaign (were I running one now) simply because of one factor...
You do not need a pirate base to get rid of stolen merchandice. A ship that comes in with forged documentation, along with a port inspector who doesn't look TOO closely at the forged documents, can feed in stolen freight to a world's infrastructure and it would look like nothing worse than the local criminals "laundering" stolen goods.
What is needed to make piracy work on a tactical level?
A region of space where the prey (the merchants) can't jump away into jump space as soon as the prey hits the 100 planetary diameters of the world they're leaving.
Such regions are:
Areas where wilderness refueling at the port world is illegal. This can happen at a desert world where the claim might be "fragile ecosystem", or it can happen at a world that has a high control rating and the "Greenies" afraid of a freighter contaminating their ecosystems with foreign lifeforms as they "dip" into the water for jump fuel.
Regions where the main world is within the shadow of a larger body such that the 100 diameter limit for the main world is inside the 100 diameter limit for the other body. A moon in orbit around a gas giant, or perhaps a main world inside the sun's 100 diameter limit.
As for other possibilities? Marc Miller spoke of "navigational accuracy" for jump space, such that the displacement error can be about 3 km per parsec, or the problem can be made worse by a factor of 10 by bad navigation and/or poor computers etc.
For those who like to include other factors in their campaign universe, I suggest the following:
Ships that precipitate into normal space by trying to exit space inside the 100 diameter limit, automatically place stresses upon the ship that can potentially add to the wear and tear of the ship itself. In addition, ships that exit unexpectedly into normal space inflict the conditions that lead to "Jump sickness". As this is a "IMTU" type of thing, the level of space sickness inflicted can vary to "moderate" to "Severe" in time duration and how likely it causes crews to be incapacitated.
The options are there - and any GM can create conditions where piracy may exist. In regions where two "national" entities are in potential competition, pirates might use the artificial boundaries of the two political entities to avoid the law enforcement arms of either side. Outlaws on one side, and model citizens on the other side of the "border" might lead to tensions building up because one "nation" doesn't want war, but also hates the piracy it has to deal with that the other side decries as "horrible", but does nothing to deter it.
Well, enough on that...
