Scholars have noted that judicial conservatism has eroded labor and employment law (hereinafter referred to as “work law”) in the U.S. and elsewhere. The Roberts Court has kept in line with such conservatism, perhaps with sharpened audacity, deciding a number of key work law cases in the favor of employers. Moreover, the current seemingly pro-employer judicial hue over recent work law cases comes at the heels of recent legal scholarship calling for a rethinking of the “idea of labor law,” the demise of the standard employment contract, and an upsurge in labor precarity. Work law, which has always been under attack, has seen better days in the U.S. But work law has experienced a rebirth in South America after years of authoritarian rule and dictatorship. There may be lessons that can be drawn from the South American experience for the U.S. and other jurisdictions where work law has suffered setbacks. One of the key institutionalized methodologies that have helped to reconstruct work law in South America has been the use of legal “principles.” This article discusses the principle of protection, perhaps the central pillar of South American work law. Under this principle, one of work law’s essential functions is to protect workers from employers because workers are “weaker parties” in employment relations. According to South American work law, worker protection is needed because workers’ weaker position puts them at the risk of being treated as commodities, a dehumanizing condition morally frowned upon in the Southern Cone. The protective principle is operationalized in South American work law through the rule of "in dubio pro operario," which essentially means that a judge or other adjudicator must rule in favor of the worker when confronting hard cases. In dubio pro operario directs adjudicators’ discretion in a manner consistent with the protective functions of work law. After describing Latin American work law’s protective principle, we turn to the U.S., namely the Fair Standards Act (“FLSA”), National Labor Relations Act (“NLRA”), and Title VII of the 1964 Civil Rights Act, perhaps the most central Federal work law statutes of the U.S., to explain how protection plays a role there. We show that, like South American work law, the FLSA and the NLRA recognize the unequal bargaining power between workers and employers. However, unlike South American work law, the NLRA and the FLSA protect workers because unequal power relations pose the risk of market failures, not because of any perceived immoral effects of commodification. On the other hand, Title VII protects workers from discrimination because of a commitment in favor of constitutional and civil rights, not because of power imbalances between workers and employers. We also show that something like the rule of in dubio pro operario sometimes prevails in the U.S. under the common law rubric that “remedial statutes should be interpreted liberally.” However, the bench and other adjudicators do not always recognize the protective nature of U.S. work law. A more explicit reference to the protective principle inherent in U.S. work law could help buttress work law in the U.S.