Dr. Muzzamil Siddiqi, former president of the Islamic Society of North America (ISNA), states the following: Originally, we are commanded to obey Allah’s commands expressed in the Qur’an and in the Sunnah. The early generations of Islam used to abide by these two sources. After the third century A.H. people started categorizing themselves to different schools and sects.
In this regard, a Muslim is to follow the Qur’an and the Sunnah; it is accessible for any Muslim who wants to know the truth.

Shedding more light on the issue, the Fatwa of the European Council for Fatwa and Research goes as follow:
“Abiding by a certain Madhhab (School of Fiqh) is not a religious obligation. Neither Allah nor His Messenger oblige us to abide by Hanafi, Maliki school or otherwise. Muslims are to abide by the Qur’an and the Sunnah. These are the two authentic, perfect, infallible sources, whereas every individual judgment is subject to acceptance and rejection. The renowned Imams themselves forbade others to unquestionably adopt their opinions.

Muslim jurists, however, agree that there is no specific Madhhab for the layman, he should abide by the Madhhab of the one who is capable of giving him a Fatwa.
the term ‘layman’ here refers to the person who cannot study the proofs of every ruling and give priority to a ruling over another. Such a person should have no Madhhab. Choosing a certain Juristic School entails giving priority and preference to certain proofs over others; this is the job for only erudite scholars. As for a commoner, he should follow the opinion of the scholar who gives him Fatwa. Whenever he has a certain problem, he can consult an Imam or a Sheikh and follow his Fatwa. Almighty Allah says: “Ask the followers of the Remembrance if ye know not!” (An-Nahl: 43) And the Messenger of Allah (peace and blessings be upon him) said concerning some people: “Why don’t they inquire if they know not, verily inquiry is the cure of ignorance.”
If an ordinary Muslim lives in a country in which all of its jurists follow a certain Madhhab, then he can follow the Madhhab adopted in his country. In fact, the common Muslim should follow the Jurists of his country and their Madhhab. But he should not insist on abiding by his Madhhab or belittle the other Madhahib. If it appears to him that the judgment pertaining to his Madhhab is weak in a certain issue, he should follow the judgment of the strong and sound Madhhab. A true Muslim always seeks the sound evidence and abides by it wherever it might be.
Imam Abu Hanifah is quoted to have said: “This is our opinion and we are ready to listen to him who brings a better opinion.” Imam Malik said: “Everyone’s opinion could be accepted or rejected except that of the one buried in this grave (pointing to the grave of the Prophet, peace and blessings be upon him). Ash-Shafi`i also said: “If a Hadith proves to be authentic (regarding a certain issue), then accept it and reject whatever religious opinion I may utter (regarding the same issue).”