Ijtihād and Taqlīd
An informative explanation from Imām Muḥammad ibn Ṣāliḥ al-ʿUthaymīn (d. AH 1421) about the linguistic and religious definition of taqlīd, as well the requirements for one to be considered a mujtahid. An additional note is added about the fatāwá of a mujtahid.
It is essential that the Mujtahid strives in expending his efforts to arrive at knowledge of the truth, and to give rulings in accordance to what is apparent to him. If he is correct, then he has two rewards: one for his ijtihād, and the other for arriving at the truth - since arriving at the truth means that it is manifested and acted upon.
DEFINITION OF IJTIHĀD:
Linguistically, ijtihād means: to expend efforts in order to reach some difficult matter. Technically it means: expending efforts to arrive at a Sharīʿah ruling. And the mujtahid is the one who expends efforts for this purpose.
CONDITIONS FOR IJTIHĀD:
Being a mujtahid has conditions, from them:-
 That he knows the Sharīʿah proofs which he needs in his ijtihād - such as the āyāt (verses) and aḥādīth pertaining to rulings.
 That he knows what relates to the authenticity or weakness of a ḥadīth, such as having knowledge of the isnād (chain of narration) and it’s narrators, and other than this.
 That he knows al-naasikh (the abrogating) and al-mansookh (the abrogated), and the places where there is ijmāʿ’ (consensus) - such that he does not give a ruling according to something that has been abrogated, nor give a ruling that opposes the (authentically related) ijmāʿ’.
 That he knows from the proofs that which causes the rulings to vary, such as takhṣīṣ (particularisation), or taqyīd (restriction), or it’s like. So he does not give a judgement which is contrary to this.
 That he knows the al-ʿArabīc language and uṣūl al-fiqh (fundamentals and principles of jurisprudence), and what relates to the meanings and indications of particular wordings - such as al-’aam (the general), al-khaass (the particular), al-mutlaq (the absolute and unrestricted), al-muqayyid (the restricted), al-mujmal (the unclarified), and al-mubayyin (the clarified), and it’s like - in order that he gives rulings in accordance with what this demands.
 That he has the ability to extract rulings from the evidence.
And ijtihâd may be split up, such that it may be undertaken in one particular branch of knowledge, or in one particular issue.
WHAT IS ESSENTIAL FOR THE MUJTAHID:
It is essential that the Mujtahid strives in expending his efforts to arrive at knowledge of the truth, and to give rulings in accordance to what is apparent to him. If he is correct, then he has two rewards: one for his ijtihād, and the other for arriving at the truth - since arriving at the truth means that it is manifested and acted upon. If, however, he is mistaken, then he has a single reward, and his error is forgiven for him - as he (ṣallallāhu ʿalayhi wa-sallam) said, “When a judge judges and strives and is correct, then he has two rewards. If he judges and strives and errs, then he has a single reward.”  If the ruling is not clear to him, then he must withhold - and in such a case, taqlîd is permissible for him, due to necessity.
TAQLEED - ITS DEFINITION:
Linguistically, taqlīd means: Placing something around the neck, which encircles the neck. Technically it means: Following he whose sayings is not a hujjah (proof).
Excluded from our saying, “Following he whose saying is not a proof.” is: following the Prophet (ṣallallāhu ʿalayhi wa-sallam), following the ijmāʿ’ and also following the saying of the Companions - for those who consider the saying of a single Companion to be a proof. So following any of these is not called taqlīd, since there is a proof for doing so. However, this type of following is sometimes referred to as taqlīd in a very metaphorical and loose sense.
THE PLACE OF TAQLEED:
Taqlīd is done in two cases:
Firstly: when the muqallid is an ’aamee (a common person) who does not have the ability to acquire knowledge of the Sharīʿah ruling by himself. So taqlīd is obligatory upon him, due to the saying of Allāh - The Most High,
“Ask the people of knowledge if you do not know.” 
So he does taqlīd of one whom he considers to be a person of knowledge and piety. If there are two such people who are equal in his view, then he chooses any one of them.
Secondly: The mujtahid when he encounters a new situation, for which an immediate solution is required, but it is not possible for him to research into this matter. So in this case, he is permitted to perform taqlīd.
Some stipulate as a condition for the permissibility of taqlīd, that the matter is not from the fundamentals of the Religion - those matters which must be held as ʿaqīdah - since matters of ʿaqīdah require certainty, whereas taqlīd only amounts to dhann (knowledge which is not certain).
However the correct saying in this matter is that this is not a condition, due to the generality of his - the Most High’s - saying, “Ask the people of knowledge if you do not know.” And this verse is in the context of affirming the Messengership - which is from the fundamentals of the Religion. And also because the common person cannot acquire knowledge of the Sharīʿah rulings with its proofs by himself. So if he is unable to arrive at the truth by himself, then nothing remains for him except taqlīd, due to the saying of Allāh - the Most High,
“Fear Allāh as much as you can.” 
TYPES OF TAQLEED:
Taqlīd is of two types: general and specific.
 The general type: that a person sticks to a particular madh′hab (school of thought), accepting it’s concessions and non-concessions, in all matters of the Religion.
The Scholars have differed about such a state. So some amongst the late-comers have reported that this is obligatory upon him, due to his inability to perform ijtihād. Others report it as being forbidden for him, due to its being a case of necessitating unrestricted following of other than the Prophet (ṣallallāhu ʿalayhi wa-sallam).
Shaykh al-Islām Ibn Taymīyyah (d.728H) said, “The saying that it is obligatory, causes obedience to other than the Prophet (ṣallallāhu ʿalayhi wa-sallam) in every matter of command and prohibition, and this is in opposition to the ijmâ’. And the allowance of it contains what it contains.”
He, raḥimahullāh, also said, “He who sticks to a particular madh′hab, and then acts in opposition to it - without making taqlīd of another scholar who has given him a ruling, nor does he use an evidence as a proof which necessitates acting in opposition to his madh′hab, nor does he have an acceptable Sharīʿah excuse which allows him to do what he has done - then such a person is a follower of his desires, doing what is ḥarām - without a Sharīʿah excuse - and this is evil and sinful.
However, if there becomes clear to him, something which necessitates preference to one saying to another - either due to detailed proofs if he knows and understands them, or because he holds one of two people to be more knowledgeable about this matter and having more piety with regards to what he says - and so he leaves the saying of that one for the saying of the other one, then this is permissible, rather, it is obligatory. And there is a text from Imām Aḥmad about this.”
 The particular type of taqlīd is that he accepts a saying about a particular matter. This is permissible if such a person is unable to arrive at knowledge of the by ijtihād - whether he is unable to in reality, or he is able, but with great difficulty.
FATWÁ OF A MUQALLID:
Allāh - the Most High - said, “Ask the people of knowledge if you do not know.” And the Ahludh-Dhikr are the Ahlul-’Ilm (the people of knowledge), whereas the muqallid is not a person of knowledge who is followed - rather he himself is a follower of someone else.
Ibn ʿAbd al-Barr (d.463) and others have said, “The people are united in ijmāʿ’ that the muqallid is not counted as being from the Ahlul-’Ilm, and that knowledge is the realisation of guidance along with it's proof.” 
Ibn al-Qayyim (d.756H) said, “And it is as Abū ʿUmar (Ibn ʿAbd al-Barr) said, “Indeed, the people do not differ about the fact that knowledge is the realisation attained from proof, but without proof, it is only taqlīd.” 
Ibn al-Qayyim then quotes, “There are three sayings about the permissibility of giving fatwá́ (legal verdict) based upon taqlīd:
Firstly: It is not permissible to give fatwá́ based upon taqlīd, because it is not knowledge; since issuing a fatwá́ without knowledge is forbidden. This is the saying of most of the Ḥanbalee scholars and the majority of the Shaafi’iyyah.
Secondly: That it is permissible with regards to himself, but it is not permissible to give a fatwâ to others based upon taqlīd.
Thirdly: That it is permissible when there is a need for it, and there is no mujtahid scholar. And this is the most correct of the sayings and is what is acted upon.”
 He is: Abū ʿAbdullāh, Muḥammad Ibn Ṣāliḥ Ibn Muḥammad Ibn al-ʿUthaymīn al-Wuhaybee at-Tamīmee. He was born in the town of ’Unayzah (Saudi al-ʿArabīa) on the 27th of the blessed month of Ramaḍān in the year 1347H. He memorised the Qurʾān during his early life and then continued seeking knowledge under two students of Shaykh ’Abdur-Raḥmān as-Saʿdī. He then continued to study under Shaykh ʿAbd al-Raḥmān Ibn Saʿdī who is considered to be his first Shaykh, since he remained with him for some time - where he studied Tawḥīd, Tafsīr, Ḥadīth, Fiqh, Uṣūl al-Fiqh, al-Faraa‘id (Laws of Inheritance), Nahw (Grammar) and Sarf (Morphology). Ibn al-ʿUthaymīn also studied under the eminent and noble Scholar, Shaykh ʿAbd al-ʿAzīz Ibn Bāz, who is considered to be his second teacher. Under him, he began studying Ṣaḥīḥ al-Bukhārī, some of the works of Shaykh al-Islām Ibn Taymīyyah, and some of the books of Fiqh. Ibn al-ʿUthaymīn says, “I was influenced by Shaykh ʿAbd al-ʿAzīz Ibn Bāz - hafiẓahullāh with regard to the great attention he gave to ḥadīth, and I was also influenced by his manners and the way in which he makes himself available to, and puts himself at the service of the people.” One of the foremost Scholars of Ahl al-Sunnah in this present age, the Shaykh is - by Allāh’s grace very active in calling the people to Allāh. Indeed, he has greatly exerted himself with this regard. The Shaykh - hafiẓahullāh has written around forty different works, some larger books and some treatises. This particular discussion on ijtihād and taqlīd has been taken from his book: al-Uṣūl min ’Ilmil-Uṣūl (p. 97-104).
 Related by al-Bukhārī (13/318) and Muslim (no. 1716)
 Sūrah al-al-Naḥl [16:43]
 Sūrah al-Taghābun [64:16]
 Jāmiʿ Bayān al-ʿIlm wa Faḍlihi (2/119)
 I’lāmul-Muwaqqi’een (l/7)