IMTU/ATU...
I thought about this in thinking about a 2350 setting and an emergence of a new UN. Since there is effectively no forum for complaining or prohibiting such practices, the nations are on their own when it comes to policing this.
Basically, my thought is that privateering requires a mass of available ships so it depends on your interpretation of the availability of space vessels.
If FTL ships become common, then privateering is a valid practice and a likely tool of nations. Instead of deploying fleets and committing military resources (likely stretched already), the commissioning of privateers is a viable strategy. Colonies are isolated and, in many cases, dependent on trade/support. So a commerce raiding campaign would have significant effects on colonial survival. The added bonus is being able to project a measure of "power" into regions where the nation may not have assets or logistical means to do so.
For example, perhaps the French are in low conflict with the Chinese. Unable to project power into the Chinese Arm makes the hiring of privateers a valuable strategy since such independent operators would be able to traverse and raid along the Chinese Arm without a French fleet movement that lacked logistical support and was observably hostile.
The flip-side is that disruption of those chains could cause serious loss of life and bad PR. For example, the effect of blocking supplies to a colony that is dependent on them would result in massive deprivation and loss of life, this could be catastrophic on a PR basis. However, it would be very effective as a cheap means of warfare.
In addition, the actions of such privateers could cause considerable difficulties for Libertine/Free Traders since the actions of privateers would make nations and colonies very aggressive towards vessels that are not authenticated friendly trade or diplomatic parties. System defense forces would become far more vigilant and hostile.
In musing further, the same could be said for mercenary organizations/commando raids. A single small raid on a colony's power plant or seed storage could cause massive disruptions to a rival.
Happily, this provides an in-game basis for the plausibility of small (character parties) skilled mercenaries and privateers to be involved in low-intensity conflicts and commerce raiding in 2300 era. The lack of an over-arching diplomatic body also contributes to this environment since we have no investigative authority or court on war crimes, space/maritime jurisdiction etc.
Canon 2300 does have a limited amount of "wild space" so the routes are likely to be more patrolled. The stutterwarp in-system capabilities also make it very difficult to entrap targets and isolate them long enough to be effective.
A tidbit picked up from MongTrav and Honorverse is also the concept of "jumpcussers." Basically, tramp traders or other groups that are opportunistic pirates but primarily merchants.
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In my Project_SN, which is highly emulative of 2300, the above has all come to the fore due to the rapid expansion of humanity (further than in 2300AD) and the many players in the stars.
My FTL drive has a down-time which makes for a better scenario of raiding. I'm still working on the in-system aspects of it but I'm keeping an eye on ensuring that piracy and privateering remains viable.
As noted, it also creates a great setting for small parties of individuals to have impact and take part in such operations (ie. adventures).
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A real-world analogy that bears mention is the discussion of Private Military Contractors. The ban against mercenary units is largely held by the global community but groups like Blackwater and the like appear to skirt under the radar because they are bona fide employees of a nation engaged in "support" and "security" operations.
http://en.wikipedia.org/wiki/Private_military_company
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