Charles Talbert makes some interesting points concerning Luke's view of the Law based on the Jerusalem decree in Acts. Rather than try to summarize his argument, I have included it in toto.
"It is clear that Luke reads the Scriptures as prophecies that are being fulfilled in Jesus and his followers. There is a new covenant in place (Luke 22:20; Acts 2). Soteriological benefits flow from the exalted Christ, not from the law (Luke 24:46–47; Acts 5:31; 10:43; 13:38–39). As a result, the repentance demanded of Israel and of Gentiles alike has to do with one's response to Jesus as Messiah (Luke 12:8-9; Acts 3:22-23). The ethnic dimensions of the law are still appropriate (Acts 21:20), though not demanded (Acts 10:28, 48), for ethnic Jews. They, moreover, have no soteriological benefits even for Jews (Acts 15:11). The only ethnic aspects of the law applicable to Gentiles are certain of those designed to facilitate social interchange between ethnic Jews and Gentiles who live among them (Lev 17–18; Acts 15:20, 29). These have no soteriological benefits for the Gentiles who observe them (Acts 15:11). Their observance by Gentile Messianists is not because of the authority of the law. It is rather because these customs are the minimalist concession that communal spirit demands to enable ethnic Jews and Gentiles, all of whom have become believers in Jesus the Messiah, to live together in unity. They are chosen not because they are a direct obligation of the law but because they are what is likely to be a source of controversy between Jewish and Gentile Messianists living together (Blomberg, 53–80; Seifrid, 39–57)."
Charles H. Talbert, Reading Acts: A Literary and Theological Commentary on the Acts of the Apostles, rev. ed. (Macon, GA: Smyth & Helwys, 2005), 135.
I am inclined to agree with Talbert. Talbert's point is even stronger for me because I do not see the prohibitions as originating in Leviticus 17-18 (see my article "A Reexamination of the Prohibitions in Acts 15," Bibliotheca Sacra 161 : 449-68).