A good lawyer has to maintain independence and a reasonable degree of impartiality. Do speak up for your client, but don't become the client's mouthpiece. When I watch the nightly news and see a defendant's lawyer protesting his client's innocence in the lobby of the Dirksen federal court building, or at the state criminal court at 26th and California, I sometimes wonder how those attorneys have so much personal knowledge of what their clients did or did not do that they can vouch for them so confidently. In the U. S. Attorney's office, we won over 90% of the federal criminal cases we brought, either because the defendant pleaded guilty or was found guilty at trial. In most cases, the defense attorney loses credibility by going too far in vouching for his clients. Perhaps the desire is to win the case on TV or the newspapers. I do not know. All I know is that it usually fails.
If you do not preserve your independence, you will not be able to advise your client, because you will be indistinguishable from him or her. You must be able to be objective, and to tell your client the bad, as well as the good, news about the case.