Hunter Biden has launched an aggressive new strategy to combat long-running federal criminal investigations and new probes promised by congressional Republicans. His legal team has sent letters to the Delaware attorney general, the Department of Justice, the I.R.S. and attorneys for Fox News and Tucker Carlson, demanding state and federal investigations into the dissemination of material from his laptop. They have also threatened a defamation lawsuit against Fox News' Tucker Carlson for allegedly failing to correct false statements. This proactive approach marks a dramatic shift in strategy for the president's son.