There are a number of limitations to what a sovereign state can do. Exogenous limits imposed by globalization, endogenous voluntary limits imposed by consent and legal limits imposed by membership of the international society of states. The extent of such limitations depends on which state is being considered and also on the period of time under consideration.
That is to say some states are more constrained than others both domestically and internationally, and that sovereign states are much more limited in their behavior in the present compared to the past. Constraints on the behavior of sovereign states are important, because such limitations are the basis by which order is maintained internationally and the rule of law respected domestically. Alternatively, constraints on the sovereign state or their absence can also be the primary source of dysfunction.
The response to the question posed will first seek to define the terms used, noting that there are multiple alternate definitions, and will then seek to outline the legal and political implications of sovereignty, arguing that whilst there are indeed a number of limitations, political implications produce an inequality amongst states that results in a hierarchy where some states have more limitations than others, which alongside conditions of anarchy is the primary source of instability and conflict globally.
The state is defined as a territorially based political unit, characterized by centralized decision making and enforcement (Chris Brown 2005). Sovereignty defined as the state as independent actor, enjoying legal supremacy over all non-state actors in making and enforcing laws. (Bayliss2005). Sovereignty is a legal status derived via recognition from other sovereign states. The legal implication of sovereignty theoretically imposes constraints, and is one of equality with other members of the society of states under international law.
Sovereignty confers a number of rights, chief among them, control over domestic affairs, self defense and freedom from outside intervention except by invitation or sanction. These rights impose two obligations which can be considered as constraints or limitations. Constraints include the duty to respect international law and not interfere with the rights of other sovereign states. These constraints are best exemplified by the twin cases of Libya and Syria.
In the case of the former, limited military intervention by NATO was permitted following sanction by the UN, and was therefore complied with international law. In contrast, military intervention has not yet been sanctioned in Syria, which as a result of the principles of non intervention and the rule of law, has allowed that state to behave in an unconstrained manner with respect to domestic political dissent. Constraints can also be self imposed and a function of domestic or international political arrangements rather than law (Zakaria).
For example the US is constrained in its behavior by liberal democratic politics, which arguably prevents it from engaging in the kind of imperialistic behavior that was previously embarked on by great powers of the past. Some states voluntary limit their behavior when they enter into cooperative agreements with other states. The inability of the Greek government to engage in a competitive devaluation of its currency or default on its debt in response to its economic problems as a result of its membership of the European Union is one such example.
All states no matter how autarkic are constrained by the globalization, no longer controlling the flow of ideas, people or goods across borders in ways they would like, and subject to the vagaries of global capital flows of an interdependent financial market place. The international drug and human trafficking industries, global warming and the 2008 financial crisis all symbolic of the limitations of the sovereign state in an increasingly globalised world. The political implication of sovereignty is one where not all states equal in law are in fact equal in their capacity to exercise sovereignty.
This produces a structural hierarchy resulting in certain states having more limitations than others, whilst other states are seemingly unconstrained. The structural hierarchy is one of a lone superpower on one end, and failed states, on the other. Such inequalities exist for political, economic or cultural reasons, leading to very different behavior and different limitations for different states within the hierarchy. The US for example was able to invade Iraq without a mandate from the UN , technically illegal and suggesting unconstrained behavior internationally.
In contrast Somalia is a failed state, nominally sovereign, but lacking effective control domestically, and is therefore extremely limited in its behavior internationally as it struggles to achieve even domestic viability. Clearly there is a practical limitation for the sovereign state, no single state can achieve global hegemony, nor can any state completely control its borders or the transformation being unleashed by processes of globalization. Whilst the legal implication of sovereignty suggests that in theory, sovereign states do have limits, those limits are frequently disregarded.
The political implication of sovereignty is a reality in which the capacity to exercise sovereignty varies dramatically from country to country, and therefore so to do their limitations. The US is clearly much less constrained than a microstate such as Lichtenstein, and it is precisely that kind of inequality and type of constraint or lack thereof, with the logical corollary of anarchy characterizing International Relations, which produces instability and is the primary source of intra and interstate conflict globally.