Instrumental agent in the passive
In formal Czech, when you use the participial passive (být + passive participle), you can state who performed the action by putting the agent in the bare instrumental case (without any prepositions).
How It Works
Forming the Agent: To name the doer (agent) in a passive sentence, decline the noun phrase into the 7th case (instrumental) without any prepositions. Do not use the preposition s (with) to mean 'by'. Alternatively, you can sometimes use the preposition od + genitive. While excellent for disambiguating the agent when the instrumental case is already used for an instrument or means (e.g., Pracovník byl vyznamenán diplomem od ředitele.), it is not a universal replacement. It specifically carries the nuance of an 'originator', 'sender', or 'author' and can sound unnatural with verbs that don't imply origin or source.
Personal Pronouns: The 'no preposition' rule applies to personal pronouns as well. Use their bare instrumental forms (mnou, tebou, jím, jí, námi, vámi, jimi). For example, 'by him' is just jím, not s ním.
Active to Passive Shift: When converting an active sentence to a passive one, the subject of the active sentence (in the nominative case) becomes the agent in the passive sentence (in the instrumental case). For example: Ředitel [NOM] chválí pracovníka. (The director praises the worker.) → Pracovník je chválen ředitelem [INST]. (The worker is praised by the director.)
Animacy and Instruments: True passive agents are overwhelmingly animate (human). If an inanimate object is used in the instrumental case with a periphrastic passive (e.g., Okno bylo rozbito kamenem. - The window was broken by a stone.), it is syntactically parsed as the instrumental of means or cause, not the agent.
Word Order: Because the expressed agent usually represents new or emphasized information, it almost always goes at the very end of the clause, following the rules of sentence-final focus.
Strict Syntactic Rule: An agent in the instrumental case can only be used with the periphrastic passive (e.g., byl postaven - was built). It is grammatically incorrect to attach an agent (the true doer of the action) to a reflexive passive (e.g., staví se - is being built). However, you can use an inanimate object in the instrumental case with the reflexive passive (e.g., Břemeno se zvedá jeřábem. - The load is lifted by a crane.) because syntactically, this is parsed as an instrumental of means (a tool used), not as the actual agent.
Verbs Governing the Instrumental: Be careful with verbs that already require their object to be in the instrumental case (e.g., opovrhovat někým - to despise someone). In the passive, the patient stays in the instrumental. Adding an instrumental agent creates a highly awkward 'double instrumental' (e.g., Zrádcem je mnou opovrhováno. - The traitor is despised by me.), which should be avoided by using the active voice instead.
Register and Style: The passive voice with an expressed agent is a hallmark of formal written registers (news, official documents, literature). Using it in casual conversation sounds incredibly heavy and unnatural. If you know who did the action, spoken Czech overwhelmingly defaults to the active voice (e.g., saying Vláda schválila návrh. - The government approved the proposal. - instead of Návrh byl schválen vládou. - The proposal was approved by the government.).
Examples (4)
- Smlouva byla podepsána oběma stranami.
The contract was signed by both parties.
Word by Word: Contract was signed both parties.
Notice that "oběma stranami" is in the bare instrumental case with no preposition.
- Pachatel byl zadržen policií.
The perpetrator was detained by the police.
Word by Word: Perpetrator was detained police.
A typical formal sentence found in news reports. In casual speech, one would simply say "Policie zadržela pachatele."
- Starý dub byl zasažen bleskem.
The old oak was struck by lightning.
Word by Word: Old oak was struck lightning.
The instrumental case is used here for a non-human agent (the force of nature) that performed the action.
- Tento román byl napsán slavným autorem.
This novel was written by a famous author.
Word by Word: This novel was written famous author.
The agent "slavným autorem" is in the instrumental. Note that for authorship outside of a passive verb, you would use "od" (e.g., román od slavného autora).
Common Mistakes
Adding the preposition 's' (with) to translate 'by'.
Dům byl postaven s architektem.Dům byl postaven architektem.Learners often try to insert s (with) to translate the English 'by'. The bare instrumental case alone expresses the agent. While od + genitive is sometimes used to avoid stacking instrumentals if the sentence already contains an instrumental of means, it is not always interchangeable and specifically implies an 'originator' or 'author'.
Using 's' with personal pronouns to express the agent.
Kniha byla napsána s ním.Kniha byla napsána jím.Just like with nouns, you must use the bare instrumental form of personal pronouns (mnou, tebou, jím, jí, námi, vámi, jimi) without the preposition s to express the agent.
Forcing an agent onto a reflexive 'se' passive.
Dům se staví dělníky.Dům je stavěn dělníky.The reflexive passive strictly forbids expressing the agent (the true doer). If you need to name the doer, you must switch to the periphrastic passive (Dům je stavěn dělníky) or use the active voice (Dělníci staví dům). Note that inanimate tools can be used with the reflexive passive (e.g., Břemeno se zvedá jeřábem) because they function grammatically as an instrumental of means, not as the agent.
How It Connects
Learn This First
To understand how to express an agent using the instrumental case in passive constructions, a learner must first be familiar with the formation of the periphrastic passive (být + passive participle) and the general functions of the instrumental case. Knowledge of participle agreement is also essential for constructing these sentences accurately.
- Instrumental of means
The use of the instrumental case to express an agent is functionally related to its use as an instrument or means, which is a more foundational use of the case.
Level 2 - Agreement of the passive participle
Since the agent in the instrumental often appears in sentences where the passive participle must agree with the subject, understanding this agreement is necessary for correct sentence construction.
Level 4
Related Patterns
- být + Passive ParticiplePeriphrastic Passive with Být
This is the type of passive construction that allows a living instrumental agent to be attached.
Level 4 - se (zvratné pasivum)Reflexive Passive with Se
The reflexive passive cannot take a living instrumental agent, though it can take an inanimate instrument.
Level 4 - Passive versus generic active agent
Explains the stylistic preference for the active voice over the passive voice in natural Czech, especially in spoken language.
Level 4 - Sentence-final focus
Explains why the expressed agent in the instrumental case is typically placed at the very end of the clause.
Level 4
Learn Next
Patterns that build on this one.
Practice Instrumental agent in the passive in Bubblegum
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