The Standard Advice
"Use active voice." It is the most repeated piece of writing advice in the English-speaking world. Grammar checkers flag passive constructions automatically. Writing guides treat passive voice like a disease. And in most cases, the advice is sound, active voice is usually clearer, more direct, and more engaging.
But "usually" is not "always." There are several situations where passive voice is the better choice, and knowing when to break the rule is what separates a careful writer from someone blindly following a style guide.
When Passive Voice Is Better
When the actor is unknown or irrelevant. "The window was broken sometime overnight" is perfectly natural. Rewriting it as "Someone broke the window sometime overnight" adds a vague actor that contributes nothing.
When you want to emphasize the recipient of the action. "The vaccine was developed in under a year" puts the focus where it belongs, on the vaccine and the speed of its creation. "Scientists developed the vaccine in under a year" shifts focus to the scientists, which may not be your point.
When you need diplomatic or neutral tone. "Mistakes were made" is a cliche, yes, but the underlying principle is legitimate. In professional writing, passive constructions can deliver bad news without pointing fingers: "The deadline was missed" lands differently than "Your team missed the deadline."
In scientific and technical writing. "The solution was heated to 100 degrees" follows the convention of scientific prose, where the method matters more than who performed it. Forcing active voice here ("The researcher heated the solution") introduces an irrelevant subject.
The Real Rule
The real rule is not "use active voice." It is "choose the voice that puts emphasis where you want it." Active voice emphasizes the doer. Passive voice emphasizes the thing done. Both are tools, and a skilled writer reaches for whichever one fits the moment.
Read your sentences aloud. If the passive version sounds clearer or more natural, keep it. No style guide should override your ear.