For a movant's case to succeed, the material offered in support of his Rule 60 (b)(6) motion must be `highly convincing

I] t is well established that a supervening change in decisional law on its own is insufficient to afford relief under Rule 60 (b)(6

The timing of the Reconsideration is undoubtedly reasonable. b. To prove a meritorious claim or defense, a movant under Rule 60 (b) does not need to show likelihood of success but must make allegations that, if established, would constitute a valid claim or defense.

However, there is a distinction between cases in which a final judgment has been entered and cases where a final judgment has not been entered.

I] f the judgment in question has been executed, and thus its effects are no longer prospective, modification of the judgment under Rule 60 (b)(6) ordinarily will be unavailable.... In contrast, where a change in law effects a consent decree or permanent injunction, a court may indeed find extraordinary circumstances present

"As the law stands today, a court may grant a motion under Rule 60 (b)(6) when the judgment was obtained by the improper conduct of the party in whose favor it was rendered or by an excusable default or in other `extraordinary circumstances.'Put simply, the applicable rule is as follows: a Rule 60 (b)(6) motion will be granted only in extraordinary circumstances or …

—noting that a mutual mistake of the law is distinguishable from a subsequent change in the law and holding that the settlement agreement entered into by the parties would be not invalidated on the basis of a subsequent change in the law

T] here is no set time period distinguishing timely from untimely motions outside of the absolute, one-year time frame for Rule 60 (b)(1)-(3) motions

Therefore, "[w] hat constitutes a reasonable time under Rule 60 (b) depends on the particular facts of the case in question."

But past settlements between the Trustees and other Coal Act obligors indicate that Coal Act obligations are "to some extent negotiable."