Despite an appeals court ruling that an obese job applicant is not necessarily entitled to protection under anti-discrimination laws, the legal landscape remains far from settled.

The issue is a pressing one for employers in light of statistics that indicate more than one-third of U.S. residents are considered obese, which the American Medical Association classified as a disease in 2013.

Observers say the 8th U.S. Circuit Court of Appeals' ruling in Melvin A. Morriss III v. BNSF Railway Co. is significant because it apparently is the first to say obesity is not necessarily a disability under the 2008 Americans with Disabilities Amendments Act.

Two other appeals courts — the 2nd Circuit in New York in 1997 and the 6th Circuit in Cincinnati in 2006 — ruled similarly to the 8th Circuit's April 5 decision, but that was before the 2008 law that broadened what is considered a disability under Americans with Disabilities Act enacted in the 1990s.

In its ruling in Morriss, a three-judge panel of the 8th Circuit in St. Louis ruled unanimously that the job applicant, whose obesity apparently was not related to other conditions such as diabetes, was not protected from discrimination when the railroad withdrew a conditional job offer after Mr. Morriss' body mass index exceeded its standard.

“The employer is entitled, according to this decision, to say, 'We don't want somebody here' because we're afraid at some point he might develop” a medical condition, said Robin E. Shea, a partner at defense law firm Constangy, Brooks, Smith & Prophete L.L.P. in Winston-Salem, North Carolina, who was not involved in the case.

As a result of the ruling, plaintiff attorneys will “be looking to attach a physiological impairment or condition as the cause of the obesity,” said Peter J. Petesch, a shareholder at Littler Mendelson P.C. in Washington. “Meanwhile, defendants will be looking to distance the characteristic from a physiological condition.”

Frank C. Morris Jr., a member of Epstein Becker & Green P.C. in Washington, said despite the ADAAA, the 8th Circuit ruling suggests that “it really does still require evidence of something beyond the mere fact of obesity” to qualify as a disability.

But in many cases, obese job applicants may have other conditions “that would qualify as an impairment as a result of obesity,” including high blood pressure, diabetes and “any number of metabolic issues,” he said.

The U.S. Centers for Disease Control and Prevention's National Center for Health Statistics has no data on the percentage of people who are obese but have no other physiological issues, a spokesman said.

However, Chattanooga, Tennessee-based disability insurer Unum Group issued a report last week blaming the high percentage of obese individuals, along with aging baby boomers, as major factors that significantly increased disability claims for joint disorders and musculoskeletal issues over the past 10 years.

The ADAAA's expanded definition of disability and the growing incidence of obesity mean “there needs to be a line” drawn somewhere, said Martha J. Zackin, a partner at Bello/Walsh L.L.P. in Boston. “There's an awful lot of obese adults in this country, and to begin claiming every incidence of obesity as a disability is taking it a bit to an extreme.”

“Time will tell” as to the ruling's significance, said Alexander P. Berg, an associate at Kollman & Saucier P.A. in Timonium, Maryland.

In light of the two other appeals court rulings, the latest decision is “part of a larger trend,” but employer clarity will have to wait until more appeals courts weigh in on the issue.

“You can never eliminate the possibility” that the Equal Employment Opportunity Commission would become a plaintiff in a case involving an obese job applicant “and test whether the 8th Circuit's decision is right under the ADAAA,” said Allan H. Weitzman, a partner at Proskauer Rose L.L.P. in Boca Raton, Florida.

An EEOC spokesman declined comment.

In appeals courts that have yet to rule on the issue, Morriss will be persuasive but not decisive, said Eric B. Meyer, a partner at Dilworth Paxson L.L.P. in Philadelphia.

“I still think you're taking a fair amount of risk if you were to simply say, 'We believe you're obese and therefore we're not going to hire you.' That would be inviting a litigation claim” where there would at least be “an open question of who would succeed,” Mr. Morris of Epstein Becker said.