Many countries attract foreign investment in the economy. The rules of law governing the movement of capital formed international investment law. One of the very important questions in the field of investment law concerned the expropriation of foreign property. The rules on expropriation of foreign investment are comprised in the so colled the minimum international standard: first-expropriation must be for a public purpose; second- even when expropriation is for a public purpose, it must be accompanied by payment of compensation for the full value of the property – or, as it is often expressed, “prompt, adequate and effective compensation”. These rules known as customary law are included in the content of treaties for the protection of investments.