(Yet in a dispute) they desire to summon one another to the...
(Yet in a dispute) they desire to summon one another to the judgment of the taghut[^1] though they were commanded to reject and disbelieve in him.”(Surah an-Nisaa, 4:60) Then 'Umar ibn Hanzalah asked, "What the two (Shi'ahs) should do then?" The Imam replied, "They must seek out one of your own who narrates our traditions, who is versed in what is permissible and what is forbidden, who is well-acquainted with our laws and ordinances, and accept him as judge and arbiter, for I appoint him as judge over you.
If the ruling which he based on our laws is rejected then this rejection will be tantamount to. ignoring the order of Allah (SWT) and rejecting us and rejecting us IS the same as rejecting Allah (SWT), and this is the same as polytheism.
[^2] In another hadith, Abi Khadijah relates that Imam Ja'far as-Sadiq (a.s.) sent him to his companions with the following message: "If a dispute or a difference occurs among you about a property, then take care not to seek judgment from those illegitimate [judges]; instead, you must seek a person who knows what is permissible and what is forbidden by us, for I appoint him as a judge over you.
And take care that you do seek judgement against one another with an unjust ruler.”[^3] The least that these two narrations prove is that the Shi'ahs are not allowed to refer to unauthorized judges for solution to their problems, instead they are advised to seek the guidance of those who are well-versed in the teachings of the Ahlul-Bayt.
In these ahadith, the practise of seeking the advice of experts in shari'ah laws is taken for granted.[^4] In Practise: There are several documented cases of Shi'ahs who asked the Imams of their time to appoint someone to adjudicate between them in religious problems. Such questions were raised by those who lived far from Medina or those who could not gain access to their Imam in Medina itself.
'Ali ibn al-Musayyab asked Imam 'Ali ar-Riza (a.s.): "I live far away and cannot always come to you, so from whom should I take the guidance for my religion?" The Imam replied, "From Zakariyyah bin Adam al-Qummi ..." 'Abdu ‘l- ‘Aziz and Hasan bin 'Ali bin Yaqtin asked Imam 'Ali ar-Riza (a.s.), "I cannot always reach to you to ask about our problems about religious teachings. Is Yunfis bin' Abdu 'r-Rahman trustworthy enough for seeking religious guidance?" The Imam replied in affirmative.