What are the conditions for someone to qualify as a marriage wali?

A wali must be Muslim, male, adult, of sound mind, free, not in ihram and not under coercion.
In the Shafi'i school, the wali must also be upright (not fasiq), although many later Shafi'i scholars accept a fasiq wali because general sinfulness is hard to avoid; this view is the one commonly practised, and specific cases should be referred to the religious affairs office. A wali who is insane, below puberty or in ihram for hajj/umrah cannot conduct a marriage; the right then passes either to the more distant wali (ab'ad) or to the wali hakim, depending on the situation. A non-Muslim father cannot be wali to his Muslim daughter. Refer to Marriage wali.