Re: Not a moment too soon
The problem of backdoors (or front-doors, or side-doors, or loft windows) is that they have to be at least as strong and well protected as the thing they are a back-door into, or they defeat it entirely.
Imagine you have something worth protecting, and you build a bunker around it that can only be penetrated with great efffort. You need to get in and out, so you install a steel door, and make sure that this is at least as hard to get through as the wall. The weakest point is the key, because someone could beat you up to get hold of it. This is all well and good, and somewhat analogous to the protection provided by, for instance SSL.
Now imagine that the governmanet decides it want sthe police to be able to access that bunker without getting a court order to get the key from you. Instead, they mandate that a second door is added to every bunker, and that this can be opened by a special police key. They also mandate how that door should be constructed, which turns out to have flaws (lets say they specify that it has to be provided by a specific door supplier, who is not an expert in security door construction, and makes then on the cheap out of plywood). This is analogous to software back-doors woudl work. You would have no knowledge of how well constructed that backdoor is, or how secure it is.
You now have two additional vulnerabilities to your security - the badly constructed back-door which may at any point be compromised more easily than your steel front-door by any random bad-guy with a sledge-hammer, and the standard police-key used to open it which may be compromised and copied by any random bad guy, without your knowledge.