What is a key function of a defense attorney in a criminal trial?

The primary role of a defense attorney in a criminal trial is to protect the rights of the accused and provide a strong defense. This involves advocating for the defendant throughout the trial process, ensuring that their legal rights are upheld, and presenting a case that challenges the prosecution's arguments. A defense attorney works to create reasonable doubt in the minds of jurors regarding the defendant's guilt, utilizing legal strategies and evidence in favor of the accused.

In fulfilling this role, the defense attorney plays a crucial part in upholding the justice system, as every defendant has the right to a robust defense, regardless of the accusations against them. This ensures that the trial process is fair and that the potential consequences of a criminal conviction, which can severely impact a person's life, are handled with the utmost care and legal diligence.

Other roles mentioned in the options, such as acting as a witness for the prosecution, ensuring a unanimous verdict, or assisting the judge, do not align with the primary responsibilities of a defense attorney. Each of these roles serves different functions within the criminal justice system but does not reflect the central duty of defending an individual's rights in a trial.