Although the Court actually did make a de facto determination of when life begins--by selecting a time during gestation before which it is legally acceptable to terminate a pregnancy by abortion--they deftly sidestepped that issue by defining the arena as one of conflicting rights under the Constitution. And, as long as the real ethical question remains hidden behind the smoke screen caused by the debate over rights, the ethics of abortion will continue to remain beyond hope for clarification.

Abortion Ethics
In reality, a useful discussion over the ethics of abortion must include two clear and distinct issues. The first is, when does life begin? The second is, when is it acceptable to terminate that life? If there is ever to be a resolution of the abortion debate, these two issues must be dealt with separately and distinctly. In this discussion, I have dealt only with the first issue. Like most people, I have a personal viewpoint on the second issue, but that is irrelevant here. At this time, I am only interested in facilitating a consensus on when life begins. Unless and until that consensus is achieved, it will be impossible to carry on a constructive debate concerning when, if ever, a pregnancy can be ethically terminated.
..... Earlier, when I set forth my reasons for believing that human life begins at implantation, the argument I presented was primarily theological. However, those who make judgements about such issues from the perspective of public policy are typically most persuaded by medical/biological arguments. So, I need to point out here that the strongest biological arguments also favor implantation as the beginning of life. In fact, as a research biologist, I was a proponent of these arguments long before I began to consider their theological implications. So, because many people are not persuaded by theological reasoning, the biological case needs to be presented. What would be the requirements for the most defensible biological definition of when life begins?
..... It will be at that point in time after which there are no discernable discontinuities in the developmental process--when everything in the process is totally predictable and nothing further occurs as a matter of chance. Recall from our earlier discussion that all of the events in early human development leading up to embryo implantation are random and relatively rare. Few of the eggs that a female produces are ever fertilized. Among the millions of sperm made available by a male, few if any are ever involved in a conception. Implantation itself is a random process, failing to occur for almost half of all conceptions and resulting in the elimination of otherwise perfectly viable embryos. Certainly, this randomness in pre-implantation developmental events makes it impossible to support a biological definition of the beginning of life that points to a time prior to the moment of successful implantation.
..... Once the embryo implants, the remainder of development is totally programmed. Nothing occurs after implantation that could be considered the kind of developmental discontinuity that would qualify it to be identified as a transition point before which the embryo/fetus was not living. Whatever point during gestation might be selected, whether based on time or developmental stage, it will be artificial--simply a random point on a continuum--and, as such, unacceptable as a mark for the beginning of life. The only logically defensible biological mark is implantation.
..... So, when the Supreme Court suggested in Rowe vs. Wade that "those trained in the respective disciplines of medicine, philosophy, and theology are unable to arrive at any consensus," they were stating a regrettable reality, but not an inevitable conclusion. The failure of consensus is not because "man's knowledge" has not advanced sufficiently to make a consensus possible, but rather because the facts issuing from that knowledge continue to be obscured by bias; bias rooted in the simple reality that it is easier to play around with the definition of when life begins than it is to enter an ethical minefield requiring decisions about when it is acceptable to terminate it. However, I believe I have shown that consensus is eminently possible. Whatever discipline is used to make the judgement, as long as irrelevant biases are eliminated, the common conclusion must be that human life begins at the moment the embryo implants in the uterus.
..... The task before us, then, is to confront and eliminate the obstructing biases. First, it should be made clear that the majority of these biases are rooted in expediency. Expediency in this case involves the need to find support for one's personal point of view on the politics of abortion. It's not about good science; it's not about good logic; it's not about good theology. It's all about expediency. It's about what position on the beginning of life gives the best support for one's particular point of view on when abortion should be permitted.
..... Thus, those whose religious beliefs compel them to categorically oppose abortion argue that life begins at conception, even though they can offer no credible theological arguments to support their position. On the other hand, those who want to see abortion allowed at some time during pregnancy will argue that procedures carried out at that time do not terminate a human life, even though they can point to no good medical evidence supporting that contention. And so it goes. The minefield that is the ethics of abortion is neatly avoided by a kind of doublethink that maintains a sliding scale on when life begins.
..... How do we get past all of these emotionally charged biases and get down to the business of seeking consensus? First, in the domain of medical science and philosophy, I believe that my scientific and logical arguments supporting implantation as the beginning of life will easily endure the objective scrutiny of scholars in those fields. I have based these arguments on the principle of "The Continuity of Development," which begins at implantation and continues, without interruption, through and beyond live birth. If any of my colleagues can identify a developmental discontinuity during normal gestation that could be considered a logical point to mark the beginning of life, I will certainly rethink my model. Until then, I believe these colleagues will be compelled to support the model.
..... So, we come to the real problem in achieving consensus; those multitudes of Christian believers who cling to the idea that life begins at conception. The simple logic of my contention goes like this:

1. Consensus on when life begins is essential before there can be a useful debate on the ethics of abortion;
2. Such consensus requires broad agreement within the disciplines of medicine, philosophy and religion;
3. There will never be strong support from medicine and philosophy for conception as the beginning of life because neither science nor common sense support it.

Ergo, unless the Christian community becomes willing to listen to what God's creation (through thoughtful scientific inquiry) is trying to tell them about itself, that community will continue to be excluded from any meaningful discussions on these critical issues...and consensus will remain impossible.
..... The fact is, there is only about a week of difference in time between fertilization and implantation. But, in the debate over ethics at the beginning of life, that week makes all the difference in the world. It not only gives us a definition of when life begins that can be agreed to by all interested parties (at least all of those who are willing to abandon unsupportable emotional attachment to their views), but it also eliminates the need for debate over several other critical issues in the biology of early human development. For example, if it is generally agreed that life begins at implantation, then all the commotion about in vitro fertilization, the use of pre-implantation embryonic stem cells for research and even experiments in human cloning will have to take a different track. We will look at each of these issues in greater detail. First, however, I would like to offer some final comments about how an agreement that life begins at implantation might affect the abortion debate.
..... Certainly it is unlikely that such a consensus would change many minds among those who currently view the option to abort a fetus as a civil right. And, even with a consensus in hand, there is no assurance that the U. S. Supreme Court would back away from its opinion in regard to the rights of the mother. I do believe, however, that it is essential for public policy in this society to recognize that, because human life begins at implantation, the willful termination of a pregnancy kills a living being. Then, and only then, can we begin the real debate over the ethics of abortion--that is, when and under what circumstances might it be ethically acceptable to take that life.
..... So, for those who wish to see public policy revisited in regard to the practice of abortion, their task is clear. They must focus on those whose disciplines the Supreme Court depends upon for wisdom in the matter of when life begins (medicine, philosophy and theology), and encourage these authorities to work for consensus. It is very unlikely that any change in public policy will ever be considered until such an agreement is achieved. And, as I see it, the only reasonable--the only possible--point of consensus is that life begins at implantation.

Research Ethics
In human embryology, the mechanism of conception has no influence on the subsequent development of the individual. That is, as long as a sperm succeeds in fertilizing an egg--wherever and whenever that event may occur--the resulting embryo can lead to a viable pregnancy...provided that it successfully implants in the uterus of the prospective mother. In vitro fertilization, for example, has become common practice in the field of medicine known as Assisted Reproduction Technology. In this procedure, sperm and eggs are isolated from prospective parents, combined in the laboratory and observed microscopically to detect evidence of conception (viable embryos). Several embryos are then injected into the uterus of the mother with the hope that one will implant. This procedure has been in use since the late 1970s. Current overall success rates are somewhat less than 20 percent.
..... Because of the rather low success rate and the high cost of these procedures, many couples opt to save some embryos and have them preserved by freezing, in the event that the first attempt does not produce a successful pregnancy. Typically, if a pregnancy does occur and results in a normal birth, the additional embryos in storage are no longer needed. The ethics of their disposition has generated significant public debate, primarily because these embryos are considered by some to be living humans and deserving of the same protections as those afforded fully developed individuals.
..... Until they implant, however, these cells have no different status than any other group of cells that have become separated from the rest of the tissues in the body--blood cells, skin cells etc. Irrespective of how it may be produced--by in vitro fertilization or by natural conception--a pre-implantation human embryo is simply a slowly dividing mass of undifferentiated cells. These cells should have no extraordinary legal status and must be considered permissible subjects for medical research.
..... The logic of this argument can be just as easily applied in the issue of human cloning. If it were relevant to this discussion, I might argue here that the practice of cloning humans is ethically questionable simply because it is difficult to see any significant benefit to be achieved from the outcome. But the issue here is not the wisdom of cloning per se, but whether or not the procedure should be regarded as "toying with life." It is certainly toying with the genetic makeup of the individual, but it is not creating a life. Life for that individual does not exist unless and until the resulting embryo has successfully implanted in the uterus of a recipient female. If it successfully implants and results in a live birth, that individual will bear the Image of God. However, as research material, pre-implantation cloned embryos should be regarded no differently than those produced naturally or by in vitro fertilization. That is, they are simply isolated human cells, and they should be considered as legitimately acceptable for use in research as any other human tissues.
..... Perhaps the most troubling ethical issue all of this raises, at least for those who regard the sanctity of life as a critical belief in their practice of religion, is the presumed possibility of creating "life in a test tube." As long as life is considered to begin at conception, then any manipulation with that "life" can be viewed as ethically unacceptable. If, however, isolated pre-implantation embryos are to be considered permissible as research material, then some investigators may be encouraged to attempt the cultivation of a living human outside the womb. Let me tell you why I think this is an unwarranted concern.
..... Certainly, there is no reason to believe that such an effort will not be attempted. Like the mountain climber who climbs "because it's there," research scientists will always be challenged by the unexplained and the unattained. In this case, however, the outcome they would be seeking is unattainable. There are some things in life that scientists will simply never be able to explain--or to duplicate. One I mentioned earlier in reference to the intimate association of the Image of God and the human capacity for cognition. There I referred to John Horgan's thoughtful book, "The Undiscovered Mind," in which he contends that modern science does not have the slightest clue how to explain consciousness in physical terms.
..... Another is the biological complexity with which we were endowed by the evolutionary process that engendered the species. When, 50 thousand years ago, God selected the creature into which he planned to invest his image, he chose the one that had already been perfected biologically according to his plan. An essential element of that perfection was a level of complexity that would forever defy reproduction by any means other than the one by which we came to be. I believe that the psalmist was writing of this uniqueness when he wrote:

and I can't imagine being able to believe these words without also believing that I have been knit together in such a fearful and wonderful way that no lesser intelligence than The Creator himself will ever be able to reproduce it.
..... We are unique, physically and metaphysically; body and soul--and we arrive at what we are through a process that not only guarantees our uniqueness, but also assures that it can never be replicated outside the parameters The Creator specified in making us what we are. There will never be "test-tube babies." "Artificial wombs" are the stuff of science fiction. Human gestation is about more than simply providing nutrition and a suitable environment for the developing embryo/fetus. It is uniqueness in process. No laboratory setup will ever come close to duplicating that experience.
..... For those who remain skeptical, I should point out that, long before anyone ever tried to create humans in the laboratory, they would have to perfect the technology using other placental mammals. Certainly, current technology has made it possible to cultivate mammalian (rat, guinea pig) embryos in vitro and to achieve development of some differentiated tissues in the cultures. In fact, this technology has significant importance in biological research; for example, in screening drugs for efficacy and toxicity. But, it's a long way from early differentiation in a Petri dish to a fully-developed animal, even a relatively primitive animal. My bet is that the technology to do even this will never be achieved. After all, we share much of our biological complexity with other placental mammals.
..... You may be wondering, however, whether accepting implantation as the beginning of life might open the door for cultivation of pre-implantation human embryos in vitro to produce differentiated tissues, like the experiments being done with rats and guinea pigs. Of course it will. In fact, if I could hazard a guess, my bet is that it has already been tried with at least some success. Am I concerned about this? Of course not. The embryos that would be used in such experiments are not human beings. They are just cells, like any others that might be isolated from tissues in the body and cultivated in vitro. In fact, it may well be that such experiments could contribute significant advances in the battle with disease by making available new tissues to replace those destroyed by infectious or physical agents, toxins or degenerative processes.
..... A general consensus that life begins at embryo implantation is not going to open the door for all kinds of horrific research on living humans. It will simply allow investigators to use their God-given talents to pursue research with pre-implantation embryonic tissues and discover more about what nature is trying to tell us about what makes us the way we are.