The Internal Revenue Code is the most authoritative source of income tax law. In

The Internal Revenue Code is the most authoritative source of income tax law. In trying to resolve an income tax question however a tax researcher also consults administrative rulings (Income Tax Regulations Revenue Rulings etc.) and court decisions. Why wouldnt the tax researcher just consult the Internal Revenue Code since it is the highest authority? Similarly why is there a need for administrative rulings and court decisions? Explain your answer.