Rules Reign Supreme: Providing Certainty When Standards Can’t

By: Billy Quinlan* & John Hill Wheliss**

About 50,000 people in the U.S. get pulled over every day.[1] A number of these individuals are believed to have broken the same legal “rule” – the speed limit. Rules are hard-edged, usually with little room for interpretation. An individual either acted in compliance with the rule or did not. Professor Carol Rose coined these hard-edged rules as “crystal.”[2] If the speed limit is 45 MPH, and you go faster than that, it is crystal clear that the rule was broken.

The law is not made up of only rules. Some laws require interpretation, and violations are not as clear as “crystal.”[3] Rose has distinguished laws of this nature as “mud.”[4] The muddiest laws are standards. “Muddy” standards require context and interpretation to determine whether the law has been broken – did you drive with a “reasonable” speed? Was there traffic? What were the weather conditions? Countless factors may come into play.

Naturally, people may prefer a law that is simple to understand and follow. So why use anything but these crystalized rules? One explanation that Rose highlighted is that, over time, crystalized rules are forced into the mud by “scoundrels,” people who use the sharp edges of rules to their advantage.[5]

Imagine a college class. A professor’s rule may be that class begins at 8:00 AM. A student not interested in complying with the rule may arrive at 8:00 AM but sleep through the entire lecture. Seeing their spirit of the rule defeated, the professor makes a new rule banning naps. Now, the student, still arriving on time, decides to abide by the napping ban and watch Netflix to entertain themselves during class. The “scoundrel” student continues to find gaps in the rules, and the professor now creates a new policy: “Arrive at a reasonable time, be prepared to learn, and participate in our discussion.” Alas, the scoundrel has forced the professor from a crystal rule into a muddy standard.

However, a scoundrel is not the only catalyst driving the shift from rules to standards. An example comes from the area of conflict of laws. Courts have historically followed one of three rules to choose the applicable law: lex loci, lex fori, or situs. Lex loci delicti directed use of tort law of the place where the harm occurred.[6] Lex fori simply applied the forum’s law.[7] Disputes over immovable property relied on situs – the laws of the place where the property sits.[8]

Unhappy with odd outcomes,[9] states began considering which jurisdiction had the “most significant relationship” to the dispute.[10] This method, called an “interest analysis,” usually weighs seven factors regarding the jurisdictions’ respective interests,[11] which then directs a court to supplemental tests with additional considerations based on the area of law.[12] While savvy litigants likely manipulated the edges of the old, crystal conflict rules, “scoundrels” alone did not cause the states to adopt tests with muddy standards like reviewing “relevant policies” and “protection of justified expectations.”[13] Ultimately, jurisdictions were chasing certain changes to rules of law that yielded unsavory results.

Regardless of the motivation being a “scoundrel” or a distaste in the results of hard-edged rules, incorporating mud and adopting standards does not fix every issue. There will always be those looking to manipulate rules, but the benefit of blocking this conduct is not worth the costs associated with increased uncertainty within and outside of litigation. A professor’s standard requiring students to arrive on time and be prepared may increase a disinterested student’s engagement with the course. But this standard comes at the detriment of students and their ability to know with certainty the professor’s expectations regarding arrival time and preparation.

Certainty is desirable. A rules-based system gives individuals the certainty as to the line between legal and illegal conduct. Rules lend certainty to individuals when valuing costs and benefits in their personal and commercial affairs.[14] For instance, rules inform individuals about what time to arrive and what speed at which they can legally operate their vehicle. Further, if there is an actual or anticipated legal dispute, they can account for the risks of liability.

When scoundrels see an opportunity, they will always be able to find a way to drive crystals into mud. But even beyond the idea of the “scoundrel” comes a distaste in the odd outcomes of certain rules, leading lawmakers to develop the aforementioned muddy standards. Regardless of who drives crystals into mud, the benefits of a sharp-edged, rules-based system surpass those provided by an ambiguous, standards-based system.

* J.D. Candidate, University of Tennessee College of Law, Class of 2025; B.S., East Tennessee State University; M.P.A. University of South Carolina.

** J.D. Candidate, University of Tennessee College of Law, Class of 2025; B.S., University of Tennessee at Chattanooga.

[1] Stanford Open Policing Project, Findings, https://openpolicing.stanford.edu/findings/ (last visited Mar. 13, 2025).

[2] Carol M. Rose, Crystals and Mud in Property Law, 40 Stan. L. Rev. 577, 577 (1988).

[3] Id. at 577.

[4] Id. at 578.

[5] Id. at 587.

[6] See, e.g., Ala. G.S.R. Co. v. Carroll, 97 Ala. 126, 131 (1892) (“[T]here can be no recovery in one state for injuries to the person sustained in another, unless the infliction of the injuries is actionable under the law of the state in which they were received.”). Similarly, lex loci contractus uses the law of the place where the contract was formed for disputes on the validity of a contract. See Scudder v. Union Nat’l Bank of Chi., 91 U.S. 406, 412 (1875); Milliken v. Pratt, 125 Mass. 374, 375 (1878) (“The general rule is that the validity of a contract is to be determined by the law of the state in which it is made; if it is valid there, it is deemed valid everywhere, and will sustain an action in the courts of a state whose laws do not permit such a contract.” (citing Scudder, 91 U.S. 406)).

[7] See Bank of U.S. v. Donnally, 33 U.S. 361, 372 (1834) (applying lex fori to a dispute regarding whether the laws of Virginia or Kentucky should apply to a debt enforcement action).

[8] See, e.g., In re Barrie’s Estate, 35 N.W.2d 658, 661 (Iowa 1949) (applying the law of the place of immovable property in dispute where parcel was improperly devised by an invalid will in another state).

[9] For example, consider a scenario where residents of State A and State B are injured a car accident in State C. Under a lex loci rule, that law of State C would apply regardless of whether the injured parties knew they were in State C or whether State C has interest in the result of litigation between two out-of-state citizens. See Tooker v. Lopez, 249 N.E.2d 394, 395–99 (N.Y. 1969) (discussing a series of cases involving guest statutes and conflict of laws in car accidents).

[10] Restatement (Second) of Conflict of Laws § 6 (1971).

[11] The “most significant relationship” test provides that:

  1. A court, subject to constitutional restrictions, will follow a statutory directive of its own state on choice of law.
  2. When there is no such directive, the factors relevant to the choice of the applicable rule of law include

(a) the needs of the interstate and international systems,

(b) the relevant policies of the forum,

(c) the relevant policies of other interested states and the relative interests of those states in the determination of the particular issue,

(d) the protection of justified expectations,(e) the basic policies underlying the particular field of law,(f) certainty, predictability and uniformity of result, and

(g) ease in the determination and application of the law to be applied.

Restatement (Second) of Conflict of Laws § 6 (1971).

[12] See id. § 145 (general principles for tort); Id. §§ 186–88 (general principles for validity of contracts and rights created thereby).

[13] Id. § 6.

[14] See Anthony D’Amato, Legal Uncertainty, 71 Cal. L. Rev. 1, 5–6 (1983) (arguing that legal uncertainty may deter conduct that states wish to incentivize, may leave individuals unsure of their entitlements, and may stifle commercial activity); see generally Uri Weiss, The Regressive Effect of Legal Uncertainty, 2019 J. Disp. Resol. 149 (2019) (arguing that uncertainty in the law transfers wealth away from risk-averse parties, creating class-regressive and gender-regressive effects that ultimately harm parties that have less bargaining power).