One strategy for decision-making involves the process known as case-based reasoning, where individuals retrieve past decisions in similar cases, compare the new and old situation, and adapt previous decisions to the new context. However, remembering past cases is a selective process. Research on retrieval-induced forgetting found that retrieving a subset of information about a certain topic causes forgetting of related information. In two experiments we use retrieval-induced forgetting to activate and deactivate similar features between a new case and past cases. We measured whether this intervention impacted decision-making about a controversial policy and whether the positive and negative outcomes of past cases influenced both information accessibility and decision-making. Study 1 demonstrated socially-shared retrieval-induced forgetting: hearing others talk about non-critical features from the past cases reduced memory accessibility of critical but unmentioned features of the positive past case (i.e., success), but not for negative past case (i.e., failure), compared with a control condition. Study 2 demonstrated that individuals' decisions were consistent with the manipulated memory pattern. Individuals were less supportive of the controversial policy in a new case when they heard non-critical information in the positive past case, whereas individuals were no less supportive when hearing non-critical information in the negative past case, compared with the control condition. We speculate that failure to trigger retrieval-induced forgetting in negative cases might be due to a negativity bias in information processing. We discuss the implication of these results for real-world phenomena involving people using the past to reason about the future.