By Nicole Tronolone
While for many February 29 is a normal day—simply a quirk of our system of leap-years—for lawyers and “Leapers” alike it presents a host of complexities and anomalies. The variance between an astronomical year and the calendar year has plagued leaders and lawyers for millennia. Dating back to 46 B.C., the lengthy history of Leap Year and the corresponding uncertainty in date and measurements of time have created a multitude of problems including uncertainty in dates of birth, sentencing requirements, contractual obligations, and filing dates. Despite its calendrical predictability, Leap Day continues to serve as a basis for litigation, providing an intriguing, if not confusing, discussion of mankind’s ability to correctly, and continuously, measure time.
In contrast to the 365-day calendar taught in primary schools, the Earth’s orbit around the sun takes 365.2422 days to complete. Because this is not an even number, the length of Earth’s orbit results in a “drift” of calendar years, with the date losing sync with holidays and seasons. Efforts to address this problem through the use of an abbreviated calendar year date back to the ancient Sumerian calendar that divided the year into twelve equal months of thirty days. Ancient Egyptians modified this calendar, tacking on five additional days of festivals to the end of the year to ensure it matched the astronomical calendar. Prior to the reign of Julius Caesar, Romans observed a 355-day year; this approach, however, had caused the seasons to drift by about three months by the time Caesar ascended to power. In response, Caesar implemented the Julian calendar. In 46 B.C. he decreed a single 445-day long year, appropriately called the “Year of Confusion,” and mandated all following years to be 365.25 days long with an additional day observed every four years. Although this solution greatly alleviated the problem, the discrepancy between the calendar and astronomical year persisted, with the astronomical year remaining eleven minutes longer than the calendar. This variation increased over time, resulting in a divergence of an entire day between the calendars every 128 years.
By the 16th century, the accumulation of these extra days had caused the Catholic holidays to shift by ten days, with Easter losing its proximity to the Jewish Passover. In the papal bull Inter gravissimus, issued on February 24, 1582, Pope Gregory XIII implemented the Gregorian Calendar to resolve the situation. Under the decree, October of 1582 lost ten days, as October 4, 1582 was directly followed by October 15, 1582. The Gregorian Calendar kept the 365 day-year used in the Julian calendar but modified the calculation of Leap Years. Today, the current calculation of Leap Days and Years follows the Gregorian Calendar. Every year divisible by four is a leap year, except for years divisible by 100. However, years divisible by 400 are leap years. The Gregorian calendar results in an average calendar year length of 365.2425 days, only twenty-six seconds longer than an astronomical year. This minimal divergence means that it will take over 3,300 years before the Gregorian calendar deviates a single day from the seasonal cycle.
The Gregorian calendar was quickly adopted by Roman-Catholic countries, while Protestant states initially rejected the change. Great Britain and its colonies, including what is now the United States, did not adopt the Gregorian Calendar until 1752, instead relying on the Julian calendar. Once Great Britain adopted the Gregorian calendar, an eleven day discrepancy remained between the two calendar system. To correct this difference Parliament accelerated the calendar “overnight” so that September 2, 1752 was immediately followed by September 14, 1752. The 200 year period of divergence from 1582 to 1752, however, created long-lasting discrepancies in interstate communication. For example, correspondence between Britain and France anytime between 1582 to 1752 written on the same day would actually carry a date discrepancy of between ten to eleven days. Perhaps one of the mostly widely known consequences of this overnight jump is the celebration of George Washington’s birthday. Although Washington’s birthday was initially reported as February 11, because he was born prior to 1752 the eleven-day skip imposed in 1752 changed his birthday to February 22.
Under the Gregorian calendar the probability of being born on February 29, Leap Day, is one in 1,461. For these “Leapers” information regarding their date of birth can become a challenging exercise in patience and ingenuity. Hospitals report mothers scheduling caesarean sections and requesting to be induced either before or after Leap Day as a result of concerns over the complexities of celebrating Leap Day birthdays with small children. Doctors have even offered to change the birth certificates of babies born on Leap Year either back dating to February 28 or forward dating to March 1, a practice that is not entirely legal.
The issues surrounding date of birth information are easily overlooked by those with birthdays that occur every year. Leapers, however, often face business and organizations registrations that do not list their birthday as an option. Even more extreme, previous healthcare IT systems have rejected February 29 as a valid date of birth. The nuisances faced by those with Leap Day birthdays include challenges regarding the effectiveness of a driver’s license that expires on February 29 or a life insurance policy that is calculated based on a birthday rather than the actual number of years lived. To address this ambiguity, most states have enacted statutes that explicitly define which date is to be used for age purposes, including the right to vote, purchase alcohol, and receive a driver’s license. In states that exclude the day of birth from such calculations, Leapers are deemed to be a year older on March 1, whereas in states that include the day of birth, a Leaper’s legal date of birth is February 28.
The confusion created by Leap Day extends far beyond birthdays, with the date a continuous source of litigation. For example, Leap Years have the potential to create additional paydays if a company’s payroll is weekly or biweekly. As a result, salaried employees who are paid on these schedules may experience one more payday in Leap Years than in others. Leap Day can also complicate the determination of timely filings and statute of limitations. Federal Rule of Civil Procedure 6(a) adopts the “anniversary method,” under which the leap day is ignored, and the final day to file is the anniversary of the event that starts the clock. Interest calculations have also been challenged, with arguments premised on the notion that interest rates based on a 360-day year, a standard bank year, leave borrowers with higher effective interest rates in Leap years.
More recently, Leap Day litigation has focused on the implications of a 366-day year on sentencing provisions. In Habibi v. Holder, the 9th Circuit addressed whether a prison term served over a Leap Year “qualifies as a ‘term of imprisonment [of] at least one year.’” Habibi, a lawful permanent resident, was convicted of a Battery of a Current or Former Significant Other in November 1999 and received a 365-day sentence that was to be served over the year 2000, a leap year. 8 U.S.C. § 1101(a)(43)(F) provides that a lawful permanent resident who commits an “aggravated felony” is ineligible to apply for cancellation of removal. As a result, the Department of Homeland security served him with a Notice to Appear, under the argument that his conviction and sentence, “made him removeable under 8 U.S.C. § 1227(a)(2)(E)(i), as an alien convicted of a crime of violence.” An immigration judge denied his request for cancellation of removal holding his conviction qualified as an “aggravated felony” under § 1101(a)(43)(F). The Immigration Judge rejected Habibi’s argument that his 365-day sentence, served during a 366-day leap year, did not qualify as an aggravated felony” because “aggravated felony” is defined as a “crime of violence . . . for which the term of imprisonment [is] at least one year.” After analyzing the complexities of calculating Leap Years, the 9th Circuit held, “In the context of § 1101(a)(43), the BIA [Board of Immigration Appeals] correctly concluded that the phrase “‘term of imprisonment [of] at least one year’ means a sentence of at least 365 days, regardless of whether any part of the sentence was served during a leap year.” The court reasoned that adopting Habibi’s argument that a “one year” sentence during a Leap Year should require 366 days would “lead to unjust and absurd results.”
Although many will regard February 29, 2020 as just another day, for some, the Leap Day presents unique complexities. 438 years after Pope Gregory XIII’s implementation of the Gregorian calendar, the variance between the astronomical and calendar year continues to generate uncertainty and legal challenges. 2020, a Leap Year, is unlikely to be an exception, witnessing a host of new and creative arguments regarding the unexpected implications of Leap Day.
 See, e.g., State v. Mason, 66 N.C. 636, 637 (1872); Habibi v. Holder, 673 F.3d 1082, 1084 (9th Cir. 2011); Kreisler & Kreisler, LLC v. Nat’l. City Bank, 657 F.3d 729, 732–33 (8th Cir. 2001); United States v. Hurst, 322 F.3d 1256, 1260 (10th Cir. 2003).
 See, e.g., Habibi, 673 F.3d at 1084 (“How many days are in a year? The answer is more complicated than it may first appear. . . . Despite its precision, the astronomical definition of a year does not help us answer the question of how long ‘one year’ is for purposes of 8 U.S.C. § 1101(a)(43)(F).”).
 Leap Year: 10 Things About 29 February, supra note 1.
 See Brian Handwerk, The Surprising History Behind Leap Year, Nat’l Geographic (Feb. 26, 2016), https://www.nationalgeographic.com/news/2016/02/160226-leap-year-science-time-world-cultures-february/#close.
 See id.
 Leap Year: 10 Things About 29 February, supra note 1; see also Handwerk, supra note 5.
 Handwerk, supra note 5.
 See id.
 See id.; see also L.E. Doggett, Calendars, NASA: Goddard Space Cent. (last visited Feb. 11, 2020), https://eclipse.gsfc.nasa.gov/SEhelp/calendars.html#Greg.
 See Doggett, supra note 11.
 See Handwerk, supra note 5.
 Doggett, supra note 11.
 See Julian/Gregorian Calendars, U. Nottingham: Manuscripts & Special Collections (last visited Feb. 11, 2020), https://www.nottingham.ac.uk/manuscriptsandspecialcollections/researchguidance/datingdocuments/juliangregorian.aspx.
 See Julian/Gregorian Calendars, supra note 18.
 See id.
 George Washington’s Birthday, Nat’l Archives (last updated June 19, 2019), https://www.archives.gov/legislative/features/washington?mod=article_inline.
 Leap Year: 10 Things About 29 February, supra note 1.
 See Meg Bryant, ‘Leap Year Babies’ Still Face Medical Records Challenges, Healthcare Dive (Feb. 29, 2016), https://www.healthcaredive.com/news/leap-year-babies-still-face-medical-records-challenges/414660/.
 See id.; see also Katie Bindley, Leap Year Babies: Expecting on February 29?, HuffPost (Feb. 28, 2012), https://www.huffpost.com/entry/leap-year-babies-2012_n_1307506.
 See Bryant, supra note 24.
 See id.
 The Leap Year and the Law, Thomson Reuters: Legal Solutions Blog (Feb. 29, 2016), https://blog.legalsolutions.thomsonreuters.com/events/the-leap-year-and-the-law/.
 See Samantha Koeninger Rittgers, 2020 is a Leap Year. Is This a Trick or Treat?, Graydon (Oct. 31, 2019), https://graydon.law/2020-is-a-leap-year-is-this-a-trick-or-treat/.
 Fed. R. Civ. P. 6(a); see also United States v. Hurst, 322 F.3d 1256, 1260 (10th Cir. 2003) (citing United States v. Marcello, 212 F.3d 1005, 1010 (7th Cir. 2000)) (“Under this rule, when a statute of limitations is measured in years, the last day for instituting the action is the anniversary date of the relevant act. The anniversary date is the ‘last day to file even when the intervening period includes the extra leap year day.’”).
 See Kreisler & Kreisler, LLC v. Nat’l. City Bank, 657 F.3d 729, 732–33 (8th Cir. 2001) (upholding 365/360 interest rate calculation included in promissory note). A 366-day year would result in 0.278% more interest paid than in a 365-day year.
 673 F.3d 1082 (9th Cir. 2011).
 See Habibi, 673 F.3d at 1086.
 Id. at 1088.
 8 U.S.C. § 1101(a)(43)(F).
 Habibi, 673 F.3d at 1088.
 Id. at 1085.
 8 U.S.C. § 1101(a)(43)(F).
 Habibi, 673 F.3d at 1086.