[2] Sayegh established the Palestine Research Center in Beirut in 1965 and served as its director-general for one year.

[7][10] Sayegh was instrumental in the establishment of Shu'un Filastiniyya which was started by the Palestine Research Center in 1971.

[11] Sayegh was one of the early scholars who analyzed the negative effects of the sectarianism in Lebanon.

"[15] He defined the racial principles of Zionism as self-segregation, exclusiveness, and supremacy which are the elements of segregation.

[16][17] Sayegh expressed empathy for all who suffer foreign occupation, urging UN delegates to uphold international law and human rights.

Against this background, he rejected the notion of Palestinian exceptionalism, emphasizing universal principles and the importance of applying them consistently.

Sayegh and other diplomats and jurists helped bring attention to the Palestinian cause within the framework of international law and human rights.