International Justice Can Be Overrated (Updated & Corrected!)
Radovan Karadzic’s arrest yesterday in Belgrade should not be celebrated as a great triumph for justice or human rights in the Balkans. A pragmatic decision was made by the new Serbian government which seeks greater integration with the EU. Justice has little to do with it for them and will bring little to his victims.
For America, the fugitive status of men like Karadzic is an issue that should retain little importance in the context of policy. His crimes have already been committed and a time when arresting or killing him would have saved lives or changed events has long past. He is joined by men like Udi Amin, Pinochet, Pol Pot, and others who were far removed from power and had diminished influence in their post-rule life. These were bad men, perhaps evil in some cases. yet they were not viable threats to peace and security after their rule was ended.
The money, time and diplomatic effort put into arresting men like this is a waste. Why, you may ask?

The US and others show little nuance in distinguishing them from those leaders who do remain significantly malevolent through their policies and actions with the influence and resources to back it up. This includes men like Mullah Omar, the Hutu Power leadership, Slobodan Milosevic and Charles Taylor.
Identifying and prosecuting the actual threats (even when sulking out of power, as Omar and Hutu Power are) should be the prime objective of talk about international justice. As such, the following steps should be considered:
1. Domestic assassination.
Commenter TM Lutas identifies the best option available in these cases in the comments section of this Duck of Minerva post discussing the merits and drawbacks of assassinating Robert Mugabe.
I think that a more interesting question is whether we should continue to spend resources (we do right now, by the way) to catch and punish any expatriate zimbabwean who would wish to assassinate Mugabe. The Westphalian principles lead us to stop private actors who wish to topple dictators and are expatriates on US soil.
The US should refrain from hassling on its soil those seeking to enact the restoration of their God-given rights by terminating the main elements of their oppression. It already has turned a blind eye towards many plots against Castro and Saddam Hussein (as more Venezuelans move to Miami, Chavez).
If local actors with expatriate/refugee support want to assassinate their oppressor (usually the type who supports similar schemes on his behalf against near-abroad enemies and rivals), I forsee more benefits than drawbacks.
2. Leveraged Buyouts.
Thomas PM Barnett speaks of the need for such an option regarding Sudan, but it has been used to some utility in the past with Serbia, Portugal and almost with Iraq. It offers a more peaceful transition than other methods, while opening up the possibility that the leader(s) could be offered a quiet vacation in an abiding third country under close surveillance of their activities.
This is not exactly justice that most have in mind but its arguably better than the status quo.
Co-opting the associates of a Bashir-type figure or the junta leaders in Burma would allow them to be taken out of the loop and removed from positions of power and influence where they could be a threat.
3. The Hunt
Hunt the individuals, their families, known associates and any assets by any means necessary. A Hutu Power cadre or Mullah Omar on the loose pose a significant security threat to a country or even a region. Most may condemn the extrajudicial killings utilized by Israel or Rwanda against their enemies and associated direct supporters, but in the end, when dealing with individuals and groups like this, intelligently applied, ruthless force may be the best option. If Rwanda had pussy-footed around with the Hutu Power cadres hiding within the Congo, it is doubtful the country would be anything close to the peaceful success it is today. Ditto for much of Israel’s strikes, which have carried domestic and international costs but have addressed at least the short and medium term security peril more ably than blind faith or ham-handed back and forth.

Rather late to comment: You state it wd be better to concentrate on “leaders who do remain significantly malevolent through their policies and actions with the influence and resources to back it up. This includes men like …, Slobodan Milosevic …”
Arrest: 2001, Death in custody: 2006.
FMC
My point was that even after his downfall, had he remained free and not been turned over to the ICC, Milosevic was sufficiently dangerous to warrant hostile action, or at the least careful, close attention. His ties and influence with the Balkan warlords and associated Serb parties and paramilitaries throughout could not be ignored.
Much like Charles Taylor (who even out of power in exile in Nigeria) who was still controlling enough warlords and associated criminal enterprises that he could cause the death of tens of thousands and/or spread rampant chaos and havoc even out of power.