From a civil point of view, the trial is between two citizens, each claiming his right in the case; they are what is called _pleaders_, and the trial itself is called a _law-suit_. The pleaders, not knowing the laws, need an intermediary to explain and defend their cause, bring it clearly to the comprehension of the magistrates and enforce its reasons. This is the part of the lawyers.
From a criminal point of view, the trial is not between two individuals; but between society and the criminal. Society, to defend itself, employs what is called a _public prosecutor_; the criminal needs a _counsel_. The part of a counsel belongs again to the lawyers.
The duties of lawyers are varied according as the cases are civil or criminal cases.
In civil law-suits, the absolute duty is the following: not to take up _bad cases_. Only it is necessary to understand well this principle. It is generally believed that a bad case is the losing one, and a good case the winning one. Thus would there in every law-suit be a lawyer who failed in his duty: the one, namely, who lost the case. This is a false idea, which very unjustly throws in many minds discredit upon the profession of the law.
Certainly there are cases where the law is so clear, jurisprudence so established, the morality so evident and imperious, that a suit having the three against itself, may be called a bad case; and the lawyer who can allow his client to believe the suit defensible, and who employs his skill and eloquence in defending it, fails in his professional duty. But this is not generally the case. In most cases, it is very difficult to tell beforehand who is right, who wrong, and precisely because it is difficult, are there judges whose proper function it is to decide. Now, in order that the judge may decide, he must be acquainted with all the details of the case; all possible reasons from both sides must be laid before him. Everybody knows that one can never of one's own account find in favor of a solution or conclusion, all the reasons which the interested party can; now, it is just that these reasons be set forth: this is the business of the lawyers. One must not forget that in every law-suit there is a pro and a con. It is for this very reason there is a suit. The lawyers are specially here to plead for the pro and con, each from his own standpoint. One could very well understand, for example, that the court should have at its disposal functionaries commissioned to prepare the cases and plead for the contending parties: one would take up Peter's cause, the other, Paul's; this is just the part of the lawyers, with this difference, that the choice of the lawyer is left to the client, because it is but just that a deputy be chosen by him he is supposed to represent.