Reclassification of NON-PORTABLE address space?

Anyone know if there is a precedent for reclassifying blocks of non-portable address space to portable? I didn’t see anything in ARIN archives (maybe I didn’t look hard enough). Bribery? Threats? Acquisition of the assignor by the assignee?

If such a reclassification were simple, I expect that the process would be heavily abused by smaller networks that would like to avoid renumbering.