TELEVISION viewers are besieged by lawyers nowadays. Whether in syndication or prime time, legal dramas seem to be on every channel, providing an alluring image of the legal system. But it's not always a recognizable one. In the plot lines of ''The Practice,'' ''Ed,'' ''Ally McBeal,'' ''Law and Order,'' ''100 Centre Street,'' ''The Court,'' ''Philly,'' ''The Guardian,'' ''Family Law'' and ''Judging Amy,'' the practice of law comes across as far more moral and emotionally complex than it is in real life.