Israel’s Law of Return.
Hebrew: חֹוק הַשְׁבוּת
The Law of Return (Hok HaShvut) was passed on 20th Tammuz, 5710 corresponding to the 5th July, 1950.
In a nutshell, the law gives Jews the right to return to, and the right to live in Israel and gain Israeli citizenship (to make Aliyah). Since 1950 there have been a few small amendments but in 1970, the right of entry and settlement was also extended to people with one Jewish grandparent or people married to a Jew, although they were not considered Jewish under Jewish law (Halacha)
Since 1970 the law applies to those born as Jews (having a Jewish mother or maternal grandmother), those with Jewish ancestry (having a Jewish father or grandfather) and converts to Judaism (Orthodox, Reform, or Conservative denominations—not secular—though Reform and Conservative conversions must take place outside the state, similar to civil marriages).
The entire law is published, in English, on the Israel Ministry of Foreign Affairs website