  We construct the most general chiral effective Lagrangian for baryon-baryon
contact interactions in flavor SU(3) up to order q^2 using a covariant power
counting. A subset of these contact terms contributes to the baryon-baryon
potential in chiral effective field theory. The Lorentz invariant effective
Lagrangian is constructed to fulfill the invariance under charge conjugation,
parity transformation, Hermitian conjugation and the local chiral symmetry
group SU(3)_L x SU(3)_R. Goldstone bosons and external fields are included as
well, thus providing additional four-baryon contact vertices involving e.g.
pseudoscalar mesons and/or photons. In order to eliminate the linearly
dependent terms, we use the Fierz identities, the equations of motion, and a
Cayley-Hamilton relation for SU(3). As an application the baryon-baryon
scattering contact potentials in low partial waves are considered.
