  We investigate self-conjugate Dark Matter (DM) particles that primarily
interact with standard model electroweak gauge bosons within an effective field
theoretical framework. Our analysis focuses on effective contact interactions,
invariant under the standard model gauge group, between Majorana fermions, and
real scalar DM, with SM neutral electroweak gauge bosons. We calculate the
Wilson coefficients for interaction terms up to dimension-8 and establish
constraints on the theory's parameters. These constraints are derived from the
observed relic density, and indirect detection observations. We discuss the
potential for dark matter-nucleon scattering in direct detection experiments.
Additionally, we utilize low-energy LEP data to assess sensitivity to the pair
production of low-mass ($\leq$ 80 GeV) DM particles. Furthermore, we highlight
the potential of the proposed International Linear Collider (ILC) in probing
effective operators through the pair production of DM particles with masses
$\geq$ 50 GeV in association with mono-photons.
