The phrase "already been employed" is correct and usable in written English.
It can be used to indicate that something has been utilized or put into use prior to the current moment.
Example: "The new software has already been employed in several departments to improve efficiency."
Alternatives: "previously utilized" or "already used".
The model has already been employed in several drug discovery projects.
In some of Bach's music the stringed instruments are played pizzicato, although this practice had already been employed by Monteverdi.
Rare earth ions have already been employed to avoid high-temperature oxidation of stainless steels and other technological alloys.
The approach leverages the Cas9 protein, which has already been employed as a Swiss Army knife for genome engineering, in a novel way.
Although Macintosh will not be expected to fulfill mousing duties -- "We don't have a mouse problem," Mr. Levi said -- she has already been employed in a unique fashion.
It may sound like one of those science fiction brain-in-a-jar movies, but many of the underlying ideas have already been employed in less ambitious ways.
These workers had been unemployed but found full-time work and have therefore lost Medicaid and other benefits; they had not already been employed full time.
The technique has already been employed in Africa in the battle against malaria and in Pakistan against dengue fever both mosquito-borne diseases like Zika.
Most are hand-me-downs that have already been employed for identity cards issued by the military and by intelligence agencies.
The antivenom is currently under production and has already been employed in the field in a pragmatic Phase III clinical trial in the Republic of Benin.
Traditional methods have already been employed in integrating databases, but these are either afflicted by their limited accuracies or restricted in their applicability ranges.
