  In this report we describe both I=2 and I=0 pi-pi scattering for twisted mass
lattice QCD utilizing twisted mass chiral perturbation theory at
next-to-leading order. Focusing on the lattice spacing (b) corrections, we
demonstrate that in the exotic I=2, I_3=+-2 channels, the leading scaling
violations of pi-pi scattering at maximal twist begin at O(m_pi^2 b^2). This is
not the case in any other isospin channel, for which the scaling violations at
maximal twist begin at O(b^2). Furthermore, we demonstrate the existence of a
mixing between the I=2, I_3 = 0 and I=0 scattering channels due to the breaking
of isospin symmetry by the twisted mass term. The mixing term, although
formally next-to-leading order, is relatively large, thus necessitating the use
of a coupled channel analysis. We argue that this mixing likely renders the
computation of the I=0 channel impractical with twisted mass lattice QCD.
