There are several different situations where the passive voice is more useful than the active voice. The passive is not “wrong”–you just have to be mindful of when you do or do not use it. Here are some common scenarios where the passive has a use:

• When you don’t know who did the action: The paper had been moved.
  • The active voice would be something like this: “Someone had moved the paper.” If you don’t know who the someone was and you want to avoid sounding like you’re blaming someone, the passive allows you to communicate the information about the paper without assigning responsibility or blame to anyone. You may or may not want the vague element of mystery this formulation entails (“Should I care who moved the paper? Why don’t we know who moved the paper??”). A mood of mystery can be especially helpful in writing fiction, but this passive construction can also signal a more straightforward lack of knowledge.
• When you know who performed the action, but you don’t consider that information important: The Petri dish had been sterilized and the new bacteria had been added. 
  • Presumably anybody would have gone through the standard procedure for sterilizing the dish in the same way and would also have followed the protocols for adding the bacteria. These cases where the methodology is prescribed and the expectation is that experimenters or researchers or students are following rules that are not individualized  (and that others in different times and places could replicate those actions to test the results) often occur in the natural and social sciences and are why those disciplines often (but not exclusively) employ the passive voice in formal writing.
• When you want to deliberately hide who did the action: The paper had been ripped.
  • Three guesses as to who ripped the paper when the speaker uses this passive formulation! Using the passive puts the focus on the paper’s fate rather than on the person who ripped it, as the culprit is completely left out of the sentence.
• When you want to emphasize the person or thing the action was done to: Clarissa was hurt by her family’s insistence on a lucrative marriage to the odious Mr. Solmes.
  • Because of the power of our narrative expectations, which lead us to anticipate that the grammatical subject of a sentence will also be the agent of the action (i.e., that we will be told a.s.a.p. in a sentence the answer to “who does what?”), we automatically focus on the subject of the sentence. Using passive to push someone who isn’t the agent into the subject position is particularly effective if your larger unit of writing (your whole paragraph, or your whole essay) focuses on that person. Here, for example, Clarissa is the heroine of an eponymous eighteenth-century novel; we can almost guarantee that an essay containing this sentence would be more about Clarissa than about the odious but minor character of Mr. Solmes, or even about Clarissa’s family’s mercenary motivations. If most sentences in this essay are active and have Clarissa as both the grammatical subject and the narrative agent, this passive construction will fit more coherently into that whole.
• A subject that can’t actually do anything: Caroline was hurt when she fell into the trees.
  • While the trees hurt Caroline, they didn’t actually do anything. Thus, it makes more sense to have Caroline as the subject rather than saying, “The trees hurt Caroline when she fell into them.” You could say, “Falling into the trees hurt Caroline” (because it’s the action of falling into trees that hurts, not trees in and of themselves), but again, you can guarantee that Caroline was the primary agent (the person performing the action that caused this hurt), and we find narratives clearer when the “who” element of “who does what?” occupies the grammatical subject position in the sentence. Notice that this formulation—Caroline was hurt—essentially renders the past participle an adjective rather than a passive construction. Other examples would include exhausted, astonished, or inebriated – there are many past participles that function like adjectives and would seem strained if you re-worded them into active constructions. How often have you ever heard anyone say, “Alcohol inebriated us” versus “We were inebriated”?

Using the Passive

Now that we know there are some instances where passive voice is the best choice, how do we use the passive voice to its fullest? The answer lies in writing direct sentences—in passive voice—that have simple subjects and verbs. This way, even if we are deviating from the usual narrative clarity of an agent in the grammatical subject position performing the action represented by the verb, we are still helping our readers to see quickly what our sentences are about. Compare the two sentences below:

• Photomicrographs were taken to facilitate easy comparison of the samples.
• Easy comparison of the samples was facilitated by the taking of photomicrographs.

Both sentences are written in the passive voice, but for most ears the first sentence is more direct and understandable, and therefore preferable. Depending on the context, it does a clearer job of telling us what was done and why it was done. Especially if this sentence appears in the “Experimental” section of a report (and thus readers already know that the authors of the report took the photomicrographs), the first sentence neatly represents what the authors actually did—took photomicrographs—and why they did it—to facilitate easy comparison. “Photomicrographs” is clearly a more useful noun to put in the subject position than “easy comparison of the samples,” which is longer and lacks any specific vocabulary, or “the taking of,” which is so awkward that we call it “turgid.”

The passive voice can also be used following relative pronouns like that and which.

• I configured the production computer environment that was provisioned for me.
• Adrián’s lab rat loves the treats that are given to him.
• Brihanna has an album that was signed by the Jonas Brothers.

In each of these sentences, it is grammatically sound to omit (or elide) the relative pronoun and to be. Elision is used with a lot of different constructions in English; we use it shorten sentences when things are understood. However, we can only use elision in certain situations, so be careful when removing words! If you aren’t confident about whether you’re eliding or just cutting information, err on the side of caution and leave all the words in place (elisions that cause confusion are a common fault when students need to revise essays to a slightly shorter length and try to shave individual words rather than cut a whole section). You may find these elided sentences more natural:

• I configured the production computer environment provisioned for me.
• Adrián’s lab rat loves the treats given to him.
• Brihanna has an album signed by the Jonas Brothers.