Passive voice has its merits. Here are three cases when writing in passive voice might improve a sentence.
1. The doer is obvious to the reader. In the example below, the assumption is that readers know who the doer is, so mentioning the doer is unnecessary.
Active: The law requires you to obey the speed limit.
Passive: You are required to obey the speed limit.
2. The doer is unimportant. In this next example, the readers care more about the resolving the sanitation problem that who resolved it:
Active: The janitor emptied the trash.
Passive: The trash was emptied.
3. The doer should be spared recognition. This final example clearly illustrates how passive voice shows greater respect to the errant employee:
Active: Hector made a mistake in the proposal.
Passive: A mistake was made in the proposal.
Understanding when to use active and passive voice will endow the writer with an invaluable tool for expressing ideas.