Robert Henry wrote:

Sure, as long as the arrival remains IFR. If the arriving aircraft is
cleared for the visual, the departing aircraft is probably not going to be
released,

Probably? I guarantee it, unless someone provides visual separation.


If the arriving
aircraft cancels IFR and proceeds direct to the field...that's different.
Now, if the tower was expecting an easterly departure, and the aircraft
proceeds west according to the ODP, then what?

Well, since he cancelled IFR it doesn't matter.


No, the tower is saying, we don't know what you are going to do, so it'd be
nice if you would tell us. Are you saying that the tower is responsible for
protecting the ODP? I don't believe that's the case, else they wouldn't
have to request a release.

The fact that a tower has to request a release has nothing to do with
the ODP. That is simply what the tower and their approach control have
worked out. I worked in the flatlands of North Dakota for a while, we
had to get a release for every IFR departure.