Many applied problems
resulting in hyperbolic conservation laws are nonstrictly hyperbolic. As of yet, there
is no comprehensive theory to describe the solutions of these systems. In this paper, a
proof of existence is given for a class of nonstrictly hyperbolic conservation laws using
a proof technique first applied by Glimm to systems of strictly hyperbolic
conservation laws. We show that Glimm’s scheme can be used to construct a
subsequence converging to a weak solution. This paper necessarily departs from
previous work in showing the existence of a convergent subsequence. A novel
functional, shown to be equivalent to the total variation norm, is defined according to
wave interactions. These interactions can be bounded without any assumptions of
strict hyperbolicity.