MURPHY, Circuit Judge. After working underground in coal mines for three decades, Casey Samons developed pneumoconiosis (commonly known as black-lung disease). His widow, Mabel Samons, sought benefits under the Black Lung Benefits Act, 30 U.S.C. §§ 901–44. It took the Department of Labor 17 years to decide (and ultimately deny) her claims. During this time, the claims bounced back and forth between an administrative law judge and the agency’s appellate body, the Benefits Review Board. In the last appeal, the Board also rejected one of Samons’s main arguments on what Samons likely views to be a legalistic ground (“law of the case”) without ever reaching the merits. The Department of Labor then delayed things further by filing an incomplete and disorganized administrative record in our court. We thus understand Samons’s frustrations with the agency’s handling of her claims. But while its actions perhaps could be described as poor customer service, they do not show any reversible legal error in the agency proceedings. To the contrary, the Board could lawfully invoke the discretionary law-of-the-case doctrine to avoid reexamining an issue on which it had affirmed the administrative law judge years before. And the judge’s credibility findings about the conflicting medical opinions pass muster under our deferential “substantial evidence” test. We thus affirm the Board’s decision.

CHAD A. READLER, Circuit Judge. At first blush, this case has the familiar attributes of a classic bribery scheme: public officeholders raising money, a lucrative public contract, and suspicious campaign contributions to those officeholders from a company seeking the contract. Those attributes led federal authorities to open a grand jury probe into bribery allegations against two Lexington City Council members. Along the way, the probe uncovered numerous illegal straw campaign contributions orchestrated by local real estate developer Timothy Wayne Wellman, purportedly as quid pro quo for choosing Wellman’s firm to fulfill the public contract. As federal investigators closed in, Wellman falsified documents and cajoled his straw contributors to lie about the fraudulent contribution scheme. That cover up proved worse than the purported underlying crime: federal prosecutors indicted Wellman for falsities and obstruction during the bribery investigation, but never bribery itself. A jury convicted Wellman on all counts.

On appeal, Wellman argues that insufficient evidence supports his convictions because, at most, he obstructed an investigation into violations of Kentucky campaign finance laws, not federal bribery. Wellman also alleges errors in his trial and sentencing. But a reasonable jury could conclude that Wellman corruptly obstructed, influenced, or impeded a federal grand jury proceeding. His other arguments are likewise unavailing. Accordingly, we affirm.