It is a tough call for some, however, so far as I am concerned, the client does not own the file and has no right to the electronic drawing. If the client wishes to have an electronic copy of the drawing, then I will provide one, but it will have to be spelled out in the contract for services.
When I am hired for a project, I am hired to provide a set of plans, when the client receives their plans, the service has been fulfilled.
We're the exact opposite. As a survey firm, we explicitly state in our contract that we expect to get electronic files for all construction surveying. If we do not, then the client must pay additional charges to recreate the files, if it is even possible. So far, this threat has been enough to ensure that we always get electronic files (except for in one instance, where the client paid to have us recreate everything). We also need the signed paper copies, and the signed paper copies are what holds in the case of dispute. So we must be careful not to blindly use the electronics, but it can save considerable time, and therefore saves the client considerable expense.
Similarly, if we do a design survey, we always make electronic files available to the client. We would much prefer that the engineers use our electronics, rather than go through the error-prone procedure of trying to recreate files from the printed copies. It saves considerable headache if everyone involved in a project uses the exact same base linework, etc., rather than constantly ending up with slightly-different versions where lines sit hundredths apart from one DWG to the other. We include disclaimers that we consider the only binding document to be the printed and signed drawings, but we also make the electronics available for use.
One of the things that we find very disturbing is the growing trend for plans to not contain enough information to recreate them without the original electronic files. We think this is a very poor tendency, brought on by laziness, but it's getting to be more and more common. It's now rare that we ever see a set of plans we could actually recreate from scratch if we had to. And periodically, we have had people resist sending us their electronics. So far, whenever that's happened, we pound the source with questions that illustrate that we CANNOT rebuild the drawings from the issued set of plans, and insist that they reissue a new set of plans that we can actually use. And so far, when given the choice of sending us electronics or reissuing plans, they've chosen to send us electronics every time.
The funny thing we've noticed, though, is that whenever we have a really hard time getting the electronic files, they always turn out to be real garbage when we finally see them...