Capacity withholding can sometimes be qualified as manipulative practice to artificially cause prices to be at a level not justified by market forces of supply and demand (including actual availability of production, storage or transportation capacity).
The precise delineation in this regard seems to be somewhat vague.
It is not a desirable situation from the perspective of legal certainty issues.
The recent ACER’s clarifications (Guidance on the application of REMIT (4th edition, updated on 15 October 2019, pkt 6.4.1 (i), p. 38, 39), although helpful, do not make the issue entirely comprehensive.
The ACER itself declares that the Agency “is committed to provide further clarifying guidance with respect to justifications mentioned in Section 6.4.1.(i)”.