Starting with general principles of public international law, the contributions in this book have shown that the legal consequences of non-recognition of States are not clearly defined in public international law and depend to a large degree on State practice. Just as recognition itself is, within some (though disputed) limits, primarily determined by political discretion, States use various approaches to address the consequences for non-recognition. Usually, States use different approaches in their treaty practice, in legislation or in the jurisprudence of national courts, often conditioned by the degree of political closeness toward specific non-recognized States. As far as can be seen, the only generally accepted rule in general public international law as to the legal consequences of non-recognition of a State is the statement of the International Court of Justice in its Namibia Opinion of 21 June 1971, according to which, even if recognition is illegal under public international law, “[125] the non-recognition … should not result in depriving the people of [the non-recognized State] of any advantages derived from international co-operation. In particular, while official acts performed by the Government of [the non-recognized State or an occupant power] are illegal and invalid, this invalidity cannot be extended to those acts, such as, for instance, the registration of births, deaths and marriages, the effects of which can be ignored only to the detriment of the inhabitants of the Territory.” Various international and national courts (mostly outside the post-Soviet region) have referred with affirmation to the Namibia formula and have tried to clarify its contents, even enlarging it to “private matters” in general.