First of all, thhe concept of national sovereignty in international law should be modified: it should be possible to do “worldwide democratic decisions” on what people are searched for because the committed severe crimes against the international community (like war crimes, genocide etc.). Such decisions can be organized in large intergovernmental organizations like the UN, in “representative democracy style” involving the UN committees. This is of course a very poor approach to world-wide decision making, but other ideas for this are lacking currently. The special thing would be that these searches would be possible without respect of national sovereignty, i.e. it would be internationally accepted (and considered a breach of sovereignty) to arrest such people in states that want to prohibit that. The new idea behind this is that national sovereignty is itself a negotiated concept, and should lose its “God-like” status that it has currently (i.e. total control over a certain part of land). The benefit would be that, if such search statements are issued against heads of state, they could be arrested in their own state without any breach of international law!
What we then need, in addition to that, is “special forces of international police”. They would be trained to execute arrests of such persons that are on these international search lists. And if this involves taking a head of government into capture, this would be done in covert operations, comparable to military operations behind enemy lines, or to secret service captures. Most of the technology for such operations still has to be developed (like capturing people by drones, etc.). The task is always to capture people alive, without hurting anybody, so that they can be brought to justice. The court that has to deal with these cases probably has to be invented also; as the ICC deals only with cases from countries that ratified the statute).
To prohibit power abuse and corruption in these international police special forces, and to get a motivated, powerful, hard-hitting group in this business that will cost many of the contributors their life, the following structure should be used: all members are volunteers; members must go through admission tests, which require extraordinal intelligence and being pure from non-rational / non-sober (mostly extremist) thinking; members undergo a 5 year education that is essentially self-regulated, but where states can contribute lectures; members are trained in this education in reflective thinking and personal decision making; every member is then free to choose, bound only by his or her own conscience, which of the search warrants to carry out; and only this international police special forces would be allowed to carry out these search warrants in the area of sovereigns who want to prohibit that; members of these special forces can organize themselves into small groups to do one or another capture, there is no central military command-and-obey principle at all; also, these people organize and invent their own equipment, the only external contribution is money, which can be paid by states but also by individuals. So perhaps individuals will start to pay for them, and to like doing so, just like it might happen with wikileaks.org or similar organizations that are a counterforce to the abuse of government power.
In the end, this idea can even lead to a new mode of “death-less” war, if applied in larger scale. War is currently an extrajuidical event, in which extrajuidical killings do happen on a regular basis. Which is a bad thing. Instead, every wrongdoer should simply be put before justice. And war should be modified as follows: the army is a group of people trained to capture the wrongdoers of the opposite side, without harming anybody. This could be particular effective in war against Guerilla groups. The principle must be to hold people personally accountable for what they do in war. The technology for this (week-long full stealth operations in enemy-controlled area, capturing by drones etc..) is not yet there, but possible.