The point of a bill of rights is to take some issues off the table of everyday law-making, unless the position can be changed by gathering some kind of constitutionally-required super-majority.
For example, Latveria might have a provision in its bill of rights prohibiting the legislature from infringing freedom of speech. If so, this will prevent its legislature from banning, say, speech that criticises religious practices or the monarch's favourite political philosophy. Since legislation to achieve that effect is beyond the power of the legislature to enact, the issue is not a matter for ordinary, day-to-day political deliberation. This has the effect of creating areas of relative safety from the intrusion of government power into Latverians' lives.
Thus, a Latverian statute banning criticism of priestly celibacy could become law only after a referendum, or whatever other mechanism was provided for in the Latverian constitution.
Of course, legislatures are notorious for testing any restrictions placed on them by bills of rights, so the political process does not come to an end in practice. We can be sure that the legislature of Latveria will make attempts, from time to time, to push the constitutional boundaries. These are then likely to be adjudicated in the country's courts, or by its constitutional commission or whatever other body has power to determine the legal issue. However, at the least, a large range of laws - those most clearly offending the relevant "right" - are unlikely to be pursued as part of ordinary politics.
None of the above is meant to deny that a bill of rights can also provide for positive rights. Just as a constitutional provision can protect us from government power, by stipulating that certain things cannot be done by the legislature (hence, a negative right), a constitutional provision can also guarantee citizens certain specific resources. For example, such a provision might require the legislature (and other branches of government if necessary) to take positive steps to ensure that everyone has access to adequate nutrition and basic healthcare.
In practice, some countries' constitutions do provide for positive rights of this kind, but those sorts of provisions are obviously open to interpretation: just what steps must be taken, and how much money spent, before it can be said that such a positive right has been satisfied? What if money is not available? For these sorts of reasons, writing in positive rights is less attractive than creating protections from government action in the form of negative rights. Traditionally, bills of rights are usually confined to negative rights - entrenched restrictions on the ability of the government to interfere with our personal choices.
It is not obvious that any of our rights should be entrenched constitutionally in such a document as a bill of rights - why not leave the resolution of our legal rights to the dynamics of the democratic political process? Many critics of constitutionally entrenched rights see them as anti-democratic.
However, one can believe that it is best for government power to be wielded by democratically-elected representatives of the people while also believing, perhaps even on the same grounds, that its scope should have some limits. If this is "anti-democratic", it is so only in some technical sense. In any event, it is widely believed that there are some things which should not be done by governments - even governments that command majority electoral support - and that it is important to provide citizens with at least some protections from government action and the possible tyranny of the majority. Just what those off-limits things might be is, of course, a matter for debate, and the actual protections can be changed from time to time by constitutional amendment.
Constitutional amendment is a more difficult process than the ordinary process for enacting legislation - sufficiently difficult, in fact, for governments not to embark lightly on the task - but that is the whole point. In practice, a legislature will have to think long and hard before it interferes with a contitutionally-protected negative right, and any attempt to do so will probably be futile.
All of which leads to the question of what a "genetic bill of rights" might contain. Its obvious content would be a set of restrictions on legislative power, designed to protect areas of important and deeply personal choices from government interference. For example, the genetic bill of rights enshrined in the constitution of Genosha might require that the legislature enact no statutes interfering with the morphological freedom of competent adults: their ability to alter themselves genetically (or in other ways) in accordance with their own decisions. I see a good deal of merit in such a proposal, but at the end of the day there are likely to be just too many complications for any jurisdiction that adopts a sweeping provision that curtails the power of its legislature in this area. Are no self-morphing actions by its citizens ever going to be socially dangerous enough to warrant prohibition or regulation?
One way to handle the issue is by having a right that is subject to some kind of override if the government can demonstrate a compelling necessity (the nature of which would have to emerge in the jurisprudence of the courts). However, I suspect that it's better to leave the matter to the normal process of policy formulation, with the legislature enacting appropriate statutes from time to time in the normal way.
That, of course, does not mean that we should simply acquiesce in any abridgment of our morphological freedom, merely because it falls within the legislature's power. It is always open to us to oppose legislative proposals that are within the law-makers' constitutional powers, and one of the grounds might well be that a particular proposal interferes unnecessarily in what competent adults plan to do with their own bodies.
While I see some merit in a constitutionally-entrenched protection of morphological freedom, even if I am slightly sceptical about it, I see no merit at all in the creation of most other kinds of constitutionally-entrenched "rights". That's especially so if the so-called rights have little to do with protecting us from government interference with our personal and important decisions.
In modern democracies, many issues - indeed, the vast majority - are best handled through the ordinary political process. For example, the Latverian legislature can enact laws forbidding human reproductive cloning, just as it can enact laws banning certain drugs, or acts of violence, or theft, or impersonating the monarch, or anything else for which there is some policy justification. Note that, whatever the situation might be in Latveria, most jurisidictions do not need a constitutional requirement that there must be a law enacted against murder. In countries like Australia and the US, we simply rely on the common law and/or the state penal code. Similarly, if there is good policy justification (which I doubt) for a law against human cloning, it can be used to support the case for ordinary laws that are enacted in the ordinary way by the legislature of the relevant jurisdiction.
Yet, we currently see bioconservatives running around talking about a genetic "bill of rights". This is misleading, for most of what they are requesting has nothing to do with establishing protections of citizens' personal choices from intrusive acts of government.
What they really want, presumably, are just ordinary laws against such things as reproductive cloning, genetic engineering, and whatever else is currently registering strongly on their yuck-meters. They are entitled to argue for that, of course, as I am entitled to oppose them, or to argue for something much more nuanced and flexible. However, talk of a genetic bill of rights creates unnecessary confusion.
With the possible exception of a broad protection from government interference in our choices about how we change our own bodies - i.e., a guarantee of morphological freedom - most issues raised in the current debates about biotechnology are totally unsuitable for anything like a genetic bill of rights.
Perhaps some new issues will arise, defining areas where we want to rein in the power of government to abuse genetic technology - taking the issue off the table for ordinary politicking. But for now, there is a fundamental problem with trying to frame policy debates about genetics in terms of the content of a new bill of rights.