Perhaps one of the most overlooked features of the U.S. Constitution is the Ninth Amendment’s instruction that “The enumeration in the Constitution, of certain rights, shall not be construed to deny or disparage others retained by the people” [1]. Despite this plain-text shielding effect on individual liberties, the Ninth Amendment seems largely ignored in the American courts. It was seldom referenced by the Supreme Court until the 1960s, when Griswold v. Connecticut (1965) finally thrust the amendment into the spotlight. In the case, Justice Douglas’s majority opinion elevated the Ninth as one of several pillars upholding a right to privacy and contraceptives, while Justice Goldberg's opinion empowered the amendment even further [2]. Since Griswold, however, the Court has largely declined to use the amendment as anything more than an interpretive guide, instead leveraging the substantive due process as the primary protector of unenumerated rights. This doctrine interprets the Fourteenth Amendment guarantee that no person shall be deprived of “life, liberty, or property” without “due process of law” as a protection of fundamental liberties from government interference, regardless of whether those liberties are deprived using fair procedures, or procedural due process [3]. While substantive due process has allowed for case-by-case protections of unlisted rights, the intended protector of such rights in the Ninth Amendment has remained neglected, despite a temporary realization of its potential power in Griswold. Still, the untapped power of the Ninth could be realized by a Court willing to reexamine its historical meaning and contemporary applications. Understanding its origins as an anticipation of the need to protect rights not presently on the minds of the founders, but relevant to future generations would guide the court through issues concerning uniquely modern rights like data privacy and transparency of automated sentencing.
Deciphering the origins and intent of the Ninth requires returning to the Federalist vs. Anti-Federalist debates. Fundamentally, the amendment was a response to Federalist concerns regarding the demands of the Anti-Federalists for a bill of rights. These worries are best summarized in Federalist No. 84, where Alexander Hamilton argues that a bill of rights would be not only unnecessary but “dangerous” [4]. By articulating exceptions to listed government powers, Hamilton feared a bill of rights would enable governments to reach for powers where they were not given. Finding a declaration of rights altogether unnecessary, he asks “why declare that things shall not be done which there is no power to do?” [5]. In other words, he believed the careful allotment of powers in the Constitution alone would provide ample protection for individual liberties. James Madison acknowledged Hamilton’s fears in his 1789 “Speech in Support of Amendments,” proposing a remedy that would ultimately become the Ninth Amendment:
“The exceptions here or elsewhere in the constitution, made in favor of particular rights, shall not be so construed as to diminish the just importance of other rights retained by the people; or as to enlarge the powers delegated by the constitution; but either as actual limitations of such powers, or as inserted merely for greater caution” [6].
Compared to the enrolled text of the Ninth, this original draft highlights how the omission of a right is not even indicative of lesser importance. Madison intended to clarify not only that unlisted rights can exist, but also that they can be just as fundamental, important, and thus protected, as those that are listed. Still, a question remains about why the Founders would choose to implement a non-exclusivity clause instead of simply enumerating every right they deem necessary to protect. The most plausible answer is their epistemic humility—the Founders understood they could not predict every right that would become relevant for the rest of history. As James Iredell stated during the 1788 North Carolina debates on constitutional ratification, “Let any one make what collection or enumeration of rights he pleases, I will immediately mention twenty or thirty more rights not contained in it” [7]. What the Founders could do, however, was inform courts that these future rights are no less important or protected than those codified by the first eight amendments.
Following its ratification, however, the Ninth was rarely invoked in courts and claims relying on it were generally unsuccessful. One example was Ashwander v. Tennessee Valley Authority (1936), in which stockholders of a Tennessee power company sued to stop the Tennessee Valley Authority (TVA) from seizing company property and equipment [8]. Arguing that Congress had no delegated power to operate an electric utility company like the TVA, the petitioners argued the federal government was encroaching on rights reserved to the states under the Tenth Amendment. Furthermore, they alleged that the government’s aggressive expansion into the free market by selling electricity produced by the Wilson Dam violated the unlisted but fundamental rights to engage in private business and commercial enterprise under the Ninth. Writing for an 8–1 Court, Chief Justice Hughes disposed of the Ninth’s invocation in a single line: the amendment, "in insuring the maintenance of the rights retained by the people, does not withdraw the rights which are expressly granted to the federal government [9].” Drawing from the Commerce and War Powers Clauses in Article I and the Property Clause of Article IV, which together empower Congress to regulate channels of interstate commerce, federal property, and military production, Justice Hughes found that Congress had constitutional authority to construct and operate the dam. He noted that the dam fulfilled a national defense purpose during World War I by contributing to munition production, was built on a channel of interstate commerce, and the electricity it produced was merely a byproduct. According to Justice Hughes, this was legitimate congressional activity that the Ninth Amendment could not invalidate [10]. Justice McReynolds, meanwhile, noted that the wartime context had long expired and improving river navigation was a mere disguise for the dam’s primary purpose: generating electricity [11]. Although Justice McReynolds was the sole, impassioned dissenter in Ashwander, even he did not take up the Ninth Amendment argument for commercial enterprise and private business; in fact, the amendment was never cited in his opinion.
Three years later, in Tennessee Electric Power Co. v. Tennessee Valley Authority (1939), the Court declined to reach the merits of the petitioners’ Fifth, Ninth, and Tenth Amendment claims [12]. The case concerned a coalition of power companies that similarly alleged the TVA’s generation and sale of electric power was federal encroachment on state and local powers. The companies argued that since the Constitution did not give Congress the power to operate a commercial utility network, that power was “reserved to the States respectively, or to the people” under the Tenth [13]. The companies also leveraged the Ninth as a protector of baseline economic liberties, including the rights to conduct business, to earn a livelihood, and to be free from overreaching government monopolies. The Ninth and Tenth together, following the companies’ arguments, created a meaningful shield against unlisted powers and a guarantor of unlisted rights. However, the Court found the companies lacked standing to sue because no specified right was being invaded [14]. Altogether, the Court demonstrated a pattern of dismantling Ninth Amendment claims.
This pattern would finally be broken in 1965, when the Court decided Griswold v. Connecticut. The case originated when C. Lee Buxton and Estelle Griswold, a gynecologist at Yale and the head of Planned Parenthood in Connecticut, respectively, opened a birth control clinic in New Haven. By operating the clinic, the two were hoping to challenge the constitutionality of a nineteenth-century Connecticut law prohibiting the use of drugs or instruments to prevent contraception and making it a crime to help anyone else do so. Following their convictions, Buxton and Griswold appealed. Their case would ultimately reach the Supreme Court, which held that the Constitution protects an unlisted but fundamental right to marital privacy against restrictions on a couple’s ability to use or be counseled in the use of contraceptives [15]. Justice Douglas, writing for the majority, argued a constitutional right to marital privacy could be construed by the “penumbras” or “emanations” of enumerated rights, including those codified in the First, Third, Fourth, and Fifth Amendments [16]. These penumbras were the surrounding protective zones of written guarantees that safeguard them from loopholes that permit government intrusion. Douglas invoked the Ninth as the protector of these penumbras.
Justice Goldberg, however, would give the Ninth an even more prominent role in the analysis: his opinion appreciated the origins of the amendment in Madison’s expectation that the Bill of Rights would not cover all fundamental rights. Then he faithfully applied its historical and plain textual intent to the present issue:
“To hold that a right so basic and fundamental and so deep rooted in our society as the right of privacy in marriage may be infringed because that right is not guaranteed in so many words by the first eight amendments to the Constitution is to ignore the Ninth Amendment and to give it no effect whatsoever” [17].
Goldberg’s opinion not only reflects a renewed historical appreciation of the Ninth, but demonstrates how it can be a sufficient protection of fundamental rights.
However, when the issue of reproductive privacy returned during Roe v. Wade (1973), the Court shifted its attention away from the Ninth. Despite acknowledging the District Court’s inference of a right to privacy under the Ninth, Justice Blackmun reasoned for the majority in Roe that the right is actually vested in the Fourteenth’s “concept of liberty” within the Due Process Clause. [18] [19]. As demonstrated nearly fifty years later in Dobbs v. Jackson Women’s Health Organization (2022), Justice Blackmun’s exclusive reliance on substantive due process in Roe weakened its capacity to withstand its challenge [20].
Justice Alito, writing for the majority in Dobbs, concluded that the right to abortion is not “deeply rooted in our history and tradition,” nor “essential to our Nation’s scheme of ordered liberty,” thus disqualifying it from the category of fundamental but unenumerated rights that substantive due process protects [21]. However, justifying the right with a substantive reading of the Ninth like Douglas’s or Goldberg’s in Griswold or the District Court’s in Roe could avoid the “deeply rooted” or “ordered liberty” test that follows Due Process claims. Some rights, regardless of their importance, are bound to fail both prongs of the test. Contemporary rights lack deeply rooted traditions to point to, and many rights, while important, are not strictly necessary to preserve the social order of liberty. Still, such rights could still persist under the umbrella protections of the unenumerated rights “retained by the people” in the Ninth [22]. Indeed, had Blackmun invoked a stronger interpretation of the Ninth in Roe, its overturning in Dobbs would have faced the additional burden of explaining why the right to an abortion could not exist under the Ninth. For future courts interested in protecting unenumerated rights with no firm tradition or necessity to the social order, the Ninth may be a better avenue to take than the Fourteenth alone.
Seven years after Roe, the Court would explicitly return to its original perception of the Ninth as a mere interpretive guideline instead of an independent source of rights in the Richmond Newspapers, Inc. v. Virginia (1980) After a judge closed a murder trial to the public, reporters from Richmond Newspapers challenged the decision on First Amendment grounds [23]. The newspaper reporters argued that First Amendment guarantees include the right to public viewing of government proceedings like trials. The Court ruled 7–1 for the newspaper, with Chief Justice Burger’s plurality opinion echoing the spirit of Griswold’s majority by finding the right of the public to attend criminal trials “implicit in the guarantees of the First Amendment.” [24]. Much like Douglas’s concept of "penumbras" of rights, Chief Justice Burger highlighted that “certain unarticulated rights” were necessary for the enjoyment of explicitly protected rights [25]. While considering the relevance of the Ninth Amendment to the case, Burger described it as a “savings clause” that supports existing rights rather than independently establishing enforceable rights [26]. Whereas Douglas and Goldberg used the Ninth in Griswold as a sword to carve out a new, substantive right, Burger used it in Richmond Newspapers as a rhetorical shield that merely affirms the implicit protections within an amendment.
The dismissive attitudes towards the Ninth were most explicitly articulated in Robert Bork’s 1987 Supreme Court nomination hearing. Comparing it to a line of mysterious text hidden by an “inkblot,” Bork insisted the amendment should be ignored by courts as its meaning is “unknown.” [27]. Bork argued that the judiciary should not fabricate the meaning of the text hidden by such an inkblot, implying Douglas and Goldberg had erred in Griswold by referencing the Ninth at all. His view never reached the Supreme Court: Bork’s nomination was rejected by the Senate 58 to 42 [28]. Still, his rejective attitude towards the Ninth echoes how Justices treated the amendment in Richmond Newspapers and the TVA cases—as an unserious basis for legal claims and too vague to have any meaning.
An opposing view later took shape in Georgetown Law professor Randy Barnett’s theory of the presumption of liberty [29]. The Ninth, according to Barnett, helps create liberty as a baseline: peaceful individual activities are protected inherently, and efforts by the government to regulate such activities should be presumed unconstitutional. This theory was effectively honored in Lawrence v. Texas (2003), when the Court found that a Texas sodomy law breached the standard of liberty as established by the Fourteenth Amendment [30]. “Liberty,” Justice Kennedy wrote, “presumes an autonomy of self” and “protects the person from unwarranted government intrusions” including regulating the sexual conduct of consenting adults, as was the case in Lawrence [30]. Although the Court used substantive due process instead of the Ninth Amendment as the vehicle for this conclusion, it did so without embracing the history and tradition tests that proved fatal to personal liberty in Dobbs. Instead, Justice Kennedy inadvertently gave effect to the principle underlying the Ninth Amendment by describing all rights involving personal autonomy as inherent in liberty, even if not explicitly enumerated or historically fundamental. The burden was on the government to justify its intrusion, and pure moral disapproval was not a sufficiently strong government interest to override the baseline personal liberty of Americans. Justice Kennedy’s omission of the Ninth, albeit erroneous, only respected decades of dismissive attitudes towards the amendment in the federal judiciary.
Although presumption of liberty and substantive Ninth Amendment approaches have rarely been applied in the courts, their relevance today is especially heightened in light of unforeseen technological developments like digital information and automated sentencing that reshape the meaning of existing individual liberties. Such changes raise questions about how existing liberties apply in new contexts and whether additional rights warrant constitutional protection. Instead of relying on Fourteenth Amendment Due Process to review particular rights on history and tradition grounds, courts should restore the Ninth to its intended role as a presumptive protection of liberty and rights unforeseen to the Founders.
The potential relevance of a more substantive interpretation became especially clear when an issue of data privacy reached the Supreme Court in Carpenter v. United States (2018) [32]. In April 2011, four men were arrested in connection with multiple armed robberies. Using the phone numbers given to the FBI by one of these men, the FBI was able to obtain transactional records from magistrate judges under the Stored Communications Act, which allows law enforcement to access non-content cellular data without a full search warrant [33]. Within these records was cell site location information, which the FBI used to charge Timothy Carpenter with robbery that affected interstate commerce under the Hobbs Act of 1946 [34]. Carpenter moved to suppress the cell site evidence on Fourth Amendment grounds, arguing the FBI needed a warrant on probable cause grounds to obtain his records. Thus, the Court had to tackle the question of how the Fourth Amendment protection against unwarranted searches and seizures applies to a new medium of privacy: digital data. Any original intent approaches to the issue are bound to produce unanswerable and arbitrary questions, as the Founders had no conception of digital technology or data privacy. The Ninth was specifically conceived to avoid needing to answer such questions. Under a substantive reading of the Ninth, new rights are presumed to exist and be no less protected than those enumerated. While the Court would go on to narrowly rule in favor of data privacy 5–4, its reasoning stretched the Fourth Amendment beyond its plain-text meaning [35]. Yet neither the parties nor the Court turned to the Ninth Amendment, overlooking a potential constitutional basis expressly concerned with rights beyond those enumerated.
Questions concerning certain unwritten rights in the age of automatic have also emerged, reemphasizing the necessity of the Ninth. The right to transparency of automated procedures that are used to deprive someone of liberty is one such case. In State v. Loomis (2016), the Wisconsin Supreme Court considered whether a sentencing court’s reliance on an opaque risk assessment software program to determine the punishment of a defendant violated the Due Process Clause of the Fourteenth Amendment. [36] The sentencing court relied on COMPAS, a software that estimates recidivism risk using a methodology hidden to both the court and the defendant. The program found that Loomis was at high risk of reoffending, which informed the court’s heavy sentencing. Loomis appealed, alleging that his inability to review how the software determined his risk of reoffending violated the Due Process Clause. He further argued that the secrecy of the methodology meant that discriminatory criteria, such as race or sex, may have been used in the risk assessment without his knowledge or the court’s and thus violated the Equal Protection Clause [37]. Although the Fourteenth Amendment guarantees that no one can be deprived of liberty without due process of law, which may involve issues of transparent adjudication, no provision in the Constitution explicitly concerns the transparency of automated sentencing. Thus, the right to which Loomis appealed could at most be implicit, which should have immediately involved the Ninth Amendment. However, Justice Bradley’s opinion for the Wisconsin Supreme Court never cited the Ninth. Had Loomis’s Fourteenth Amendment claims been coupled with a substantive Ninth claim, Justice Bradley would have been unable to ignore the amendment. Even if the Ninth does not protect any one right in particular, its pairing with the Fourteenth, as Goldberg did in Griswold, would legitimize the unwritten freedoms of the Constitution. Nonetheless, despite the important implications of the case, the Supreme Court denied writ of certiorari in 2017 [38]. The questions of whether an unenumerated right to transparency of automated sentencing exists and whether the Ninth Amendment helps infer such a right still remain unanswered by the Supreme Court.
Still, some have expressed concern for the conception of a baseline liberty. Critics have argued the approach would give judges a blank check to invent rights. However, the presumption of liberty provides a framework for judicial decision-making while limiting judges’ discretion. Courts already recognize personal liberties as being necessarily limited: freedom of speech is not construed to protect yelling “Fire!” in a crowded theater, nor is the right to keep and bear arms construed to protect private ownership of weapons of mass destruction [39][40]. When a sufficiently significant government interest is at stake, or when a law can be reasonably tied to a delegated congressional authority, the government action is still valid under a presumption of liberty. Recognizing a baseline presumption of liberty would place the burden on the government to justify its interference, rather than on individuals to establish that their freedom deserves protection.
Additionally, the alternative mechanism of protecting unlisted rights through substantive due process would risk repeating the mistakes of Lochner-era jurisprudence. The Court routinely invoked Due Process to strike down protective labor laws like minimum wages, maximum hour regulations, and union protections under the guise of an unarticulated “freedom of contract.” [41][42][43]. Continuing down the Fourteenth Amendment Due Process path risks opening the door to similar misapplications that effectively inhibit liberties rather than protecting them. A substantive Ninth Amendment interpretation, however, is less susceptible to harmful judicial inventions. Goldberg, whose concurrence in Griswold emphasized the Ninth’s interpretive significance, explicitly stated the amendment is not “an independent source of rights protected from infringement by either the States or the Federal Government” [44]. Even at its greatest extent of substantive interpretation, the Ninth is necessarily checked by its dependence on other amendments. A substantive Ninth interpretation is not intended to serve as open discretion for judges, but rather a meaningful check on restrictions concerning real liberties.
It is unfortunate that despite hundreds of years of adjudication, the single use of the Ninth Amendment by a Supreme Court Justice that fully acknowledged its creator’s intentions, respected its plain-text meaning, and realized its potential as a tool of liberty was Goldberg’s concurrence in Griswold v. Connecticut. Yet the relevance of the Ninth Amendment will only increase as social, technological, and political progress reveal the necessity of rights unforeseeable to the Founders and, consequently, left unenumerated. Other avenues of protecting unlisted rights, such as the Fourteenth Amendment Due Process, have faced the obstacles of case-by-case recognition and reliance on expanding the Fourteenth’s meaning beyond its plain text and original intent, demonstrated by Roe’s overturning in Dobbs. History and tradition tests also impede substantive due process in modern contexts: the greater the technological progression that sources the need for a right, the harder it is to justify that right under the historical tests that accompany Fourteenth Amendment’s Due Process Clause. With the door still open to modern applications in contexts of data privacy, consumer protections from AI deception, and countless other contemporary mediums, the Court should return to the Ninth and give it its long-overdue legal effect.