Novice writers tend to overuse passive voice. To combat this, many writing teachers advise students never to use passive voice.
Passive voice places the emphasis on the result of the action or the receiver of the action, rather than the actor or the action itself. This is appropriate in cases where the actor is unknown, unimportant, impersonal, or anonymous. Passive voice often expresses itself in policies or rules.
Smoking is prohibited in all areas of the building.
Scientific writing often uses passive voice to describe procedures or experiments.
A solution of one part sodium chloride and three parts water was prepared.
Passive Voice can also be a kind of scapegoat, to avoid saying who did what.
The new regulation was approved without debate or public comment.
Who approved it, and why did they do so in secret? This passive sentence does not tell us.
Too many sentences in passive voice make a written passage wordy, sluggish, and dull. Use passive voice only where it is absolutely needed so that it will not lose its effect.