To start, let me make clear that the hypothetical we're discussing involves a lab that uses "illicit material," which is, for example, human embryos or cell lines created from human embryos. (This post is not about the Jackson laboratory that may or may not be built in Ave Maria Town. I haven't done sufficient research to know what scientific practices would occur at the Ave Maria lab if it was constructed.)
In 2008, the Vatican issued an "Instruction Dignitas Personae" which commented on various bioethical issues, including "The use of human 'biological material' of illicit origin." Paragraphs 34 and 35 of the instruction make clear that any research on "illicit material," even material that was obtained in a manner completely separate from the research lab, is not permitted. In other words, mere independence from the evil actions that produced the illicit material is not sufficient. This is because there is an additional duty "to avoid cooperation in evil and scandal."
Commenter "anonymous" reads the Instruction as permitting a person to work in a lab where illicit material research is occurring, "so long as he does not use the illicit material, he uses whatever authority he has to prevent use of illicit material, and takes appropriate measures to decry the use of illicit material so as to avoid scandal."
This is incorrect because "anonymous" is only thinking that there is a duty to avoid scandal, and he is ignoring that there is also a duty to avoid cooperation with evil.
Of course, for a better explanation I need to turn to Fumare hero, Professor Charles E. Rice. In his book, The Winning Side, page 229, Rice explains some important concepts:
Formal cooperation in evil, which is never morally justified, therefore consists of "direct participation" in the evil act "or a sharing in the immoral intention of the person committing it." (Evangelium Vitae, no. 74). Evangelium Vitae did not explicitly state the principles of material, as opposed to formal cooperation. "Material cooperation is that in which the cooperator performs an act which in itself is not wrong, though it is used by the principal agent to help him commit sin. This type of cooperation, as opposed to formal cooperation in evil, is not always wrong. Its morality depends on the proximity to the immoral act itself and whether there is a proportionate reason. Thus, material cooperation may be either proximate or remote." (Rev. Edward Hayes et al., Catholicism and Ethics: A Medical/Moral Handbook (1997), 72).In the Vatican Instruction, only one example is given of a connection to experimentation on illicit material that is so remote that it is permissible: a parent using a vaccine necessary for the health of a child that was developed using cell lines of illicit origin. Even in that case, there is still a duty to make known one's disagreement with the evil (which is an appropriate measure so as to avoid scandal).
Now there are many different levels of involvement with the evil of human embryo research, from the parent's use of a vaccine to the researcher's actual experimentation on human embryos. One of those levels of involvement is if a person was employed at a lab where human embryo research was being done. A few examples include a janitor who cleans the lab where human embryo research occurs, an IT technician who fixes the computer on which the human embryo researcher works, or a lab assistant who prepares the microscope and slides for his researcher boss. In these instances, the employees would not be using illicit material and they would not have the authority to prevent such use. Let us also assume that these employees loudly decry the use of the illicit material to anyone who will listen so as to avoid any possibility of scandal. In all these instances, the employees would still be materially cooperating with evil. This is so because, in the words I quoted above from The Winning Side, they would be " perform[ing[ an act which in itself is not wrong, though it is used by the principal agent to help him commit sin."
Some material cooperation with evil is entirely permissible. In his book, Rice talks about material cooperation with evil in the context of abortion and quotes a pastoral statement which discusses the example of a hospital worker who cleans an operating room where abortions are sometimes performed. "The worker may oppose abortion and intend only to facilitate the morally upright, indeed laudable, surgical procedures performed there. He or she merely accepts as an unintended albeit foreseen consequence that the well-maintained facility will enable physicians to perform abortions." (page 231). This is given as an example where the hospital employee's actions might be morally permissible.
In the abortion context, it is easy to imagine nurses with even higher levels of material cooperation with abortion: for example, there is the nurse who holds the scalpel for the abortionist. For both the worker who cleans the operating room and the nurse who holds the scalpel, both employees aren't formally or directly participating in the abortion, as the abortion would still occur if they weren't there, but since their actions do help the abortionist commit the evil, both are instances of material cooperation. Assuming that both employees loudly decry the abortion so as to avoid scandal, the morality of their actions depends on their proximity to the abortion and whether there is a proportionate reason for their actions. Even assuming that the nurse who holds the scalpel makes known to everyone that she disapproves about abortion so as to avoid scandal, she might be so connected to the abortion such that her actions are impermissible and immoral.
Back to our original question: Is it moral to work at a lab where there is human embryo research?
The answer: It depends "on the proximity to the immoral act itself and whether there is a proportionate reason." For the janitor who cleans the lab where human embryo research occurs, his actions might be sufficiently remote so that his actions are morally permissible, especially if the janitor has a proportionate reason for his employment at the lab (like if he truly needs the money and this is the only job he can find). But for the lab assistant who prepares the equipment for his researcher boss, even assuming that the lab assistant declares to everyone around him that he disapproves of the research thereby avoiding scandal, his actions might be too connected to the immorality of human embryo research, especially if the lab assistant has an equivalent employment opportunity at a neighboring non-human embryo research lab. Merely taking "appropriate measures to decry the use of illicit material so as to avoid scandal," as "anonymous" argues, is sometimes not enough.