Black's law dictionary is used in many cases.
Constitutional law depends on what you want to question the meaning of. It is not unknown to go back to the debate the colonies were having before the constitution was written. Re: bill of rights, yep we have none, and next to no human rights. Even the right to jury trials is very limited. Our rights to freedoms and rights to information are being eroded over time by governments, mainly liberals, wanting to take our rights away to combat terrorism and hide their actions from the people they supposedly represent. Representative democracy in Australia is on its deathbed.