What about "peer" pressure?
From the article: "Although advocates of the sharia process stressed that participation in the tribunal process would be voluntary, some critics expressed concern that many Muslims would be labeled disobedient if they refused participation in such sharia-based arbitrations.
"If I am a woman of faith, and the community of people who see themselves as leaders say that if I do not follow the sharia court here, the Islamic Institute, then I will be tantamount to blasphemy and apostasy," Hogben said in a debate shown on Canadian television. "And you know that in some countries, apostasy means death sentence."
The same peer pressure exists among ultra-Orthodox Jewish groups (Hassidim). If a Hassid summons another Hassid to appear before a din torah (a rabbinic tribunal) and the latter refuses, all the other Hassidim are supposed to shun him. Nonetheless, U.S. courts routinely enforce the decrees of these Rabbinic tribunals.