They have no doubt that the person or group that they will represent is in the right. In other words, they believe that the person or group that they will represent is morally justified in their case. The ethical nature of the case is moral as opposed to immoral. Generally, lawyers prefer to represent people that are morally justified, instead of working in the defense of a clearly presumed criminal like a murderer.

"...ethical nature of the case. " This means that this case has a moral side to it and touches on moral principles that need to be considered when handling this case, not just the legal principles.

"...ethical nature of the case. " This means that this case has a moral side to it and touches on moral principles that need to be considered when handing this case, not just the legal principles.