In a recent X thread, U.S. Sen. Mike Lee (R-Utah), suggested that an effective, in fact “amazing,” tool to combat drug cartels would be the re-implementation of letters of marque—a since-discarded 18th-century wartime naval practice that authorizes private individuals and companies to attack and capture enemy vessels or property.
The proposal quickly found its way to members of President Trump’s inner circle. Donald Trump Jr. praised the idea as “an effective, efficient, @DOGE-compliant way to combat Mexican drug cartels.” Elon Musk, the head of the Department of Government Efficiency (DOGE), offered that “[t]his would work very fast.”
A short two weeks later, a bill was introduced in the U.S. House to “authorize President Trump to commission privately armed and equipped actors to seize the persons and property of any cartel, cartel member, or cartel-linked organizations.”
Given this potential traction, it is worth a closer look at letters of marque and what their utilization would entail. A review of their historical function, the legal and diplomatic challenges involved in reintroducing them, and the strategic risks of adopting such an approach provides a timely reminder that the U.S. abandoned any policy of unleashing unregulated private actors in armed conflicts for good reason. Attempting to revive it now would undermine U.S. legal norms, create diplomatic instability, and risk unintended escalation.
Such outcomes have made themselves evident even in private military action short of letters of marque, with private military contractors (PMCs) crossing ethical and legal boundaries and facilitating corruption—as demonstrated in the cases of Blackwater and the Wagner Group, respectively. This has been the case even as PMCs directly contract with their respective client governments and fall within a far narrower scope and clear chain of command—elements of control that are intentionally discarded in letters of marque.
Historical Background
A letter of marque and reprisal is a government-issued commission authorizing private individuals, historically known as privateers, to conduct military-style operations on behalf of a state. The practice was common from the late Middle Ages through the early 19th century, particularly among maritime nations that lacked the time or resources to build strong standing navies. Privateers were permitted to seize enemy ships and cargo in wartime, keeping a portion of the profits as compensation.
The U.S. Constitution explicitly acknowledges letters of marque: Article I, Section 8, Clause 11, grants Congress the power to issue them. The practice was used during the American Revolution and the War of 1812 as a way to supplement the naval capabilities of the young republic. However, privateering quickly became legally and diplomatically problematic—with the publicly operated naval ships causing far less collateral damage and operating cohesively with one another. By the mid-19th century, it was recognized as an unreliable and destabilizing tool of war, leading to its near-total abolition.
One of the primary reasons for this shift was the difficulty of regulating privateers. Many operated with little regard for international law, blurring the line between sanctioned warfare and piracy. The decline in privateering occurred as the norm that war between nations should be waged by public authority grew stronger.
In 1823, then-Secretary of State John Quincy Adams wrote that any nation that renounced the slave trade should also renounce this commercial raiding. The House Committee on Foreign Relations, as part of a larger wish to “confine the immediate injuries of war to those whose sex, and age, and occupation, do not unfit them for the struggle,” hoped to ensure “the security of fair and harmless commerce from all attack,” achieving “the mitigation of a barbarous code.” That same year, President Monroe spoke of the “amelioration of the condition of the human race which would result from the abolition of private war on the sea.”
Concerns about accountability and escalation ultimately led to the 1856 Declaration of Paris, in which major naval powers, including Britain and France, formally abolished privateering. The treaty stated unequivocally that privateering is and remains abolished. While the United States did not sign the treaty, it adhered to its principles, recognizing that the era of private military commissions had passed. The last formal U.S. use of letters of marque was during the War of 1812.
Since then, no major power has issued a letter of marque, as modern military and legal frameworks have evolved to prohibit private warfare. The closest version we see today is the use of PMCs–though, as noted above, these entities technically exist within a contract framework with their client states that should technically provide inherent oversight and control. Russia’s Wagner Group pushes the boundaries of such a formalized relationship, as they take on additional client states and non-contract action that blurs their lines of accounting more than the standard PMC or mercenary group. With at least two centuries worth of state practice anchoring the nonuse of, and a reasonably clear opinio juris, it seems the abolishment of true privateering would, at this point, be well-settled customary international law under which even the U.S., as a nonsignatory, would be obliged to follow.
An argument does exist that the U.S. has staked out a reservation to this norm as a persistent objector—though the strength of this argument rests on a relatively sparse set of objections that were, at the time, rooted solely in the fact that the U.S. did not have a standing navy that could compete with other major nations.
Meanwhile, penalties for unauthorized pirating are enshrined in U.S. federal law under 18 U.S.C. Chapter 81. Section 1651 of the statute proclaims that, “[w]hoever, on the high seas, commits the crime of piracy as defined by the law of nations … shall be imprisoned for life.” Meanwhile, Section 1661 brings these penalties onshore, stating broadly that, “[w]hoever, being engaged in any piratical cruise or enterprise, or being of the crew of any piratical vessel, lands from such vessel and commits robbery on shore, is a pirate, and shall be imprisoned for life.”
There is some gray area here as to just how far onshore such laws extend, but between the two systems of laws, it seems that any piratical enterprise activity would land an individual in front of either a federal district court or the Hague.
Beyond the Law
In his proposal, Sen. Lee seemingly addressed such concerns over the legal barriers, explaining that the use of letters would “undoubtedly draw criticism, especially from those inclined to elevate abstract, often-inchoate principles of what they deem ‘international law’ above the sovereign interests of the United States.” He explained that dismissing their use “on the basis of ‘international law’ or otherwise … overlooks the clear and present threat posed by those cartels to the U.S.” He concluded, “This could prove to be an effective alternative to war.”
Should the Trump administration take up Lee’s proposal, it would certainly not be the first time a U.S. administration viewed international law as suggestive rather than prescriptive. But international law is the lowest hurdle faced here, compared to U.S. domestic laws forbidding such activity and the diplomatic repercussions that would surely follow. And Lee’s conclusion that these drawbacks would be in pursuit of “an effective alternative to war” betrays even the most basic calculation of what might result from such a strategy. The law in this case, though significant, is just the first hurdle. Even more fraught are the strategic realities of such an approach.
These strategic reasons include diplomatic concerns, the sophisticated warfare capacity of cartels, risks of corruption, challenges in attribution, and risks of escalation within Mexico and elsewhere, including China.
The diplomatic implications of issuing letters of marque would be severe. If private actors sanctioned, or at least left alone, by the U.S. government conducted military-style raids in Mexico or another sovereign nation, it would almost certainly be considered an act of war. The Mexican government has already rejected past suggestions that the U.S. directly intervene against cartels, even when framed as counterterrorism operations. Deploying private military forces under letters of marque would be an even greater violation of sovereignty, likely prompting diplomatic retaliation and further complicating U.S.-Mexico law enforcement cooperation.
The proposal to use letters of marque against drug cartels bears striking similarities to an earlier U.S. attempt to combat another set of non-state criminal actors—pirates and smugglers in the Caribbean during the early 19th century. Much like modern drug cartels, these groups operated outside traditional warfare, controlled key trade routes, and amassed immense wealth through illicit enterprises. The United States, facing increasing disruptions to commerce and security, initially turned to private actors as part of its anti-piracy efforts. However, the results of this approach underscore why deploying privateers against cartels today would likely be ineffective and counterproductive.
Following the War of 1812, piracy surged in the Caribbean, particularly along the Florida coast, in the Gulf of Mexico, and near Spanish-controlled Cuba. These pirates and smugglers were not merely isolated raiders; they operated in sophisticated networks with established bases and connections to corrupt officials. Spanish authorities often tolerated or even facilitated smuggling in Cuba, while pirate bands frequently secured safe harbor in remote inlets and unpatrolled coastal regions. These groups financed their operations through stolen cargo, ransoms, and illicit trade, much like contemporary drug cartels.
Rather than relying solely on the U.S. Navy, Congress issued letters of marque to private captains, hoping that privateers would aggressively target known pirate vessels while operating at a lower cost than regular naval forces. However, this strategy quickly spun out of control. Many privateers, acting with minimal oversight, began attacking neutral merchant vessels and even American-flagged ships, justifying their actions under dubious interpretations of their commissions. Others formed covert alliances with smugglers, accepting bribes or directly participating in illegal trade. The inherent profit motive of these private actors often led them to prioritize personal gain over broader law enforcement objectives.
Recognizing the failures of privateering, the U.S. government abandoned the model and established a professional, state-controlled force to address piracy. In 1822, the Navy created the West Indies Anti-Piracy Squadron, which operated under direct government oversight and engaged in a sustained, systematic campaign to suppress piracy and smuggling. This approach ultimately proved successful, as increased naval patrols, direct engagements with pirate strongholds, and coordination with local authorities led to a dramatic reduction in maritime crime by the mid-1820s.
The same problems that plagued the privateering approach against Caribbean smugglers—lack of oversight, legal ambiguity, diplomatic fallout, and private actors prioritizing profit over public policy—would inevitably arise in any attempt to use letters of marque against drug cartels today. The evolution of U.S. anti-piracy strategy in the 19th century underscores the broader reality that countering well-financed transnational criminal organizations requires coordinated, professionalized state-led efforts, not profit-driven mercenaries.
Today’s landscape carries the added risk of indirect escalation with major geopolitical adversaries. Chinese actors and markets are increasingly intertwined in Mexico’s cartel economies, such as drug and wildlife trafficking and money laundering. If U.S.-sanctioned private actors disrupted cartel financial networks or supply chains linked to Chinese businesses, it could complicate an already critically fragile relationship and even provoke retaliatory measures. There is also a clear risk of mission creep for the commissions granted to privateers—how wide of a scope could they pursue in an effort to combat cartel activity?
Modern Parallels
There have been other recent attempts to justify the use of letters of marque in modern conflicts—attempts that have, also, largely reinforced why the practice remains obsolete. Recent proposals include the use of privateers against Russian oligarchs and cyber threats.
In 2022, Rep. Lance Gooden (R-Texas) introduced H.R. 6869, a bill that would authorize private American citizens to seize the assets of Russian oligarchs as a punitive measure in response to Russia’s invasion of Ukraine. The idea was that, rather than relying solely on government sanctions and asset freezes, letters of marque would allow private actors to seize Russian-owned yachts, planes, and other high-value assets, keeping a portion of their value as a financial incentive. Gooden framed the bill as a way to empower Americans to disrupt Putin’s inner circle while avoiding direct military escalation.
This proposal was criticized as impractical, legally dubious, and strategically reckless. Vanderbilt Law School’s Ingrid Brunk, a known authority on letters of marque, called it “an awful idea,” pointing out that letters of marque were historically used in naval warfare, not financial enforcement. She further warned that authorizing private actors to seize foreign assets would blur the line between law enforcement and piracy, potentially provoking diplomatic retaliation and escalating hostilities. This concern is particularly relevant in the case of Russia, a nuclear-armed adversary with significant retaliatory capabilities in cyber, financial, and energy domains.
Beyond the legal and diplomatic risks, there were practical enforcement concerns. Ownership structures of high-value assets are often complex, with many yachts and corporate holdings shielded by shell companies, cross-jurisdictional investments, and multinational ownership stakes. Brunk cautioned that private actors given letters of marque would have every incentive to target assets indiscriminately, leading to potential seizures of neutral or even American-owned property—a scenario eerily reminiscent of how 19th-century privateers frequently overstepped their commissions, attacking neutral and even allied shipping for profit.
A similarly flawed proposal emerged in the context of cybersecurity. Some, including a former general counsel of the Air Force, have floated the idea of issuing letters of marque to private hackers, allowing them to conduct offensive cyber operations against foreign state actors or criminal organizations. Proponents argue that this could serve as a cost-effective way to bolster U.S. cyber capabilities while deterring potential threats.
However, the same fundamental problems persist. Attribution in cyberspace is notoriously difficult—hacking groups often conceal their origins or operate under false flags, meaning that a U.S.-sanctioned cyber privateer could easily target the wrong entity, escalate international tensions, or even get played into attacking an unintended third party. Additionally, private hackers would have little incentive to operate within the bounds of international law, raising the likelihood of indiscriminate cyberattacks, financial crime, and collateral damage.
These are persistent flaws in the privateering model. Letters of marque create a dangerous mix of profit motives, loose oversight, and high geopolitical risk. Just as privateers of the past, modern actors empowered by letters of marque would have every incentive to push beyond their original mission, exploit legal loopholes, and provoke unintended conflicts.
Even beyond the specific case of letters of marque, the mixture of private profit incentives and military activity has rarely succeeded. Whether through privateers, mercenary groups, or modern military contractors, history repeatedly shows that when military action becomes a business venture rather than a state-controlled function, problems inevitably follow.
One of the most well-known modern examples is Blackwater’s operations in Iraq. Originally contracted by the U.S. government to provide security and logistical support, Blackwater’s private military personnel quickly became involved in unregulated violence, including the 2007 Nisour Square massacre, where Blackwater operatives killed 20 Iraqi civilians. The backlash was immediate, with Iraqi authorities demanding accountability and the U.S. struggling to rein in private contractors operating outside traditional military oversight.
Maybe the closest thing to modern letters of marque can be seen in modern-day conflicts involving Russian Wagner Group forces around the globe, where private economic interests—largely approved by the Russian state—have driven military action with a primary focus on resource extraction and Russian strategic interests.
While history has shown the dangers of mixing profit incentives with military force, the United States has successfully deployed financial incentives in other areas to root out bad actors—without handing enforcement power to private individuals. Programs designed to combat fraud, corruption, and illegal financial activity have proved highly effective because they reward those who provide valuable intelligence but leave investigatory and enforcement actions to professional government agencies with clear oversight and accountability.
Examples include the Securities and Exchange Commission’s Whistleblower Program, which provides whistleblowers with 10 to 30 percent of the monetary sanctions collected—with program payouts totaling more than $1 billion—and the Internal Revenue Service’s Whistleblower Office, offering 15 to 30 percent of revenue collected and with program payouts also totaling more than $1 billion.
In fact, such a program already exists to target the drug cartels. The U.S. Department of State’s Narcotics Rewards Program offers up to $25 million for information leading to the arrest of narcotics traffickers. The program touts several successes, including the arrests of heads of drug trafficking organizations, and the prosecution of more than 75 major foreign violators of U.S. narcotics laws, and total payouts of over $135 million to tipsters.
These systems work because they leverage financial incentives in a way that supports professionalized, regulated enforcement mechanisms, rather than empowering individuals to act as enforcers themselves.
– Peter Neal is a Deputy Public Defender in the Los Angeles County Public Defender’s Office and a Captain in the US Army Reserves where he serves as a Judge Advocate. Published courtesy of Lawfare.
