Al-jawab billahi at-taufeeq (the answer with Allah's guidance)
1) Please read the book 'The Legal Status of Following A Madhab' By Mufti Taqi Uthmani.
2) The question that arises is why should one follow any of the four Imaams?
This can be answered by posing a counter-question: "Do you know all the various laws of Deen? Are you capable of extracting and deriving the laws pertaining to wudhu, salaah, zakaah, etc. directly from the Qur'an and Hadith? Do you know which Hadith has abrogated another? Do you have the ability to reconcile between the various Ahadith which apparently contradict each other? Do you know which verses of the Qur'an are general in their application and which verses are qualified by other texts? etc., etc." If one does not have the knowledge of these aspects, then one definitely does not have the ability to derive the laws directly from the Qur'an and Hadith. In that case the following aayah applies directly to oneself: "Ask those of knowledge if you do not know." (16:43 & 21:7) Hence when we do not have the enormous amount of knowledge and expertise that is necessary to derive the laws directly from the Qur'an and Hadith, we have opted to follow one of those great people who had attained that distinguished mastery in this field, among whom is Imaam Abu Hanifa, also Imam Shafi, Imam Malik and Imam Ahmad (RA).
Please check this site: http://www.ummah.net/Al_adaab/fiqh/taqleed.html Please also check: http://www.muftisays.com/index.php?d=articles&viewpage=zntaqleed
