Many of Jack Coggins's books still have current copyright protection in his name - however, the current situation is very complicated.
When Jack Coggins died in 2006 he left his estate, including copyright management, to be handled by his attorney, for the benefit of his wife Alma. She has since passed away, so the estate was then managed for the benefit of a local Art Institute. Unfortunately the attorney has recently passed away also, so the estate management and copyright issues are currently in limbo until a new management team is appointed, which is currently in progress. Therefore it will not be possible to gain permission to use any copyrighted material until the new appointment is finalised.
Up to the present time there has been no problem using Jack's illustrations for strictly non-profit purposes, and I would suggest that this may still be the case. However, this is not a legal opinion and I can't give any legal permission to use any images. The use of Jack's illustrations for profit or commercial purposes is a different matter, and would not be allowed without legal permission. I will be listing contact details of the new copyright management team here as soon as I have them.
Some of Jack's illustrations are covered by copyright held by publishers and/or other authors. I will try to assist with enquiries about copyright issues if possible - please email me with details.