<p> In his monograph [Ne], Nekovar studies cohomological invariants of big Galois representations and looks at the variations of Selmer groups attached to intermediate number fields in a commutative p-adic Lie extension. In view of the formulation of the "main conjecture" for noncommutative extensions, it seems natural to extend the theory to a noncommutative p-adic Lie extension. This thesis will serve as a first step in an extension of this theory, namely, we will develop duality theorems over a noncommutative p-adic Lie extension which are extensions of Tate local duality, Poitou-Tate global duality and Grothendieck duality. </p> / Thesis / Doctor of Philosophy (PhD)