Complex litigation refers to legal cases that involve multiple parties, intricate factual and legal issues, and require extensive pre-trial proceedings. These types of lawsuits often involve large sums of money or significant public interest, and can take years to resolve due to their complexity. They typically require a high level of expertise from attorneys on both sides, as well as judges who must navigate through the intricacies of the case. Examples of complex litigation include class action lawsuits, product liability cases, and intellectual property disputes.