Detecting Under the Microscope: It's not Illegal is It? Depends

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Metal detectorist John Howland advises the readers of Dick Stout's blog:

nor, is it illegal for rally organisers or anyone else to ‘seed’ fields with genuine, low-value, non-treasure roman coins either as single ‘plants’ or as ‘pretend’ hoards. 

Several years ago rally organizers would (against a growing body of suspicion) strenuously deny such practices were taking place, now we see a general acceptance that it is going on. This seems to me tacit admission that the most 'productive' sites have already been "hammered" and no longer produce the array of finds that once could have been expected of them.

Is it indeed the case that no law is broken by the described practice? Well, the first point is that the discoverer of what appears to be a hoard is obliged by law to report it to the Coroner (like the discovery of human remains even if they do seem to be very old). It is up to the coroner to determine the facts of the case after the report. Anyone not reporting such finds is breaking the law.

Secondly dumping extraneous matter, whatever it is, on somebody else's property is illegal in the absence of formal permission. Thirdly, it is a matter of no little significance where those "genuine, low-value, non-treasure Roman coins" came from. Can they be documented as legally obtained material? Obviously disposing of stolen goods on somebody else's property is not legal. Similarly, if the finds are 'plants;' of stolen material, a person who comes into their possession by 'finding' them does not thereby gain legal title to them, since they were stolen in the first place. This is important if he has paid for admission to the land on the explicit or implicit understanding that he will gain legal title to any low-value non-Treasure find he may there discover. If legal title is impossible to obtain by virtue of the origins of the 'planted' material, selling tickets to such an event amounts to fraud.

That is of course leaving aside totally the ethical issues of contaminating the archaeological record with imported material. An additional factor is the mantra that artefact hunters are "searching for history", but if the resource they are exploiting has been artificially created in recent times, then they are searching for a pseudo-history, a made-up history, a false history.  Who are they trying to kid? They are not searching to enlarge anybody's knowledge of the history of an area, they are searching for things to collect. Nothing else. This is no more archaeology than stamp collecting.