Consensus by definition means widespread agreement, or absence of any dissent. Consensus means general agreement without serious opposition. Scientific consensus means that all major scientific organizations and journals relevant to the issue endorse a proposition, whether or not public opinion agrees. Some scientists may disagree but are unable to convince a major group to endorse an alternative view.
Most legislative bodies operate by consensus on routine matters, saving roll calls for disputed questions. The only major organization in the world to operate on unanimous consensus is the North Atlantic Treaty Organization (NATO). Every decision that NATO makes must be either agreed on by all of its members or at least not opposed by any of its members.
The Polish legislature or "Sejm" in the 17th and 18th centuries operated by unanimous consensus. Foreign governments routinely bribed members to vote no, and the result was a very weak state that in the 1790s was carved up by its neighbors.