Shelby Houlihan is listed on the “start list” at the U.S. track and field Olympic trials that begin on Friday despite receiving a recent four-year ban after failing a drug test. Whether she actually makes it to the starting line, however, appears to be in doubt. 

Houlihan is the elite runner who earlier this week said she had been issued a four-year ban from the sport in a ruling by the international Court of Arbitration for Sport. She blamed a tainted burrito for a steroid detected in her testing sample. But on Thursday, she was listed as an entrant in the 1,500-meter and 5,000-meter races Friday in Eugene, Ore. She is the American record holder at both distances.

USA Track and Field, the sport’s domestic governing body, issued a statement Thursday from Susan Hazzard, USATF Managing Director of Communications, that appeared to apply to Houlihan: “Given there is an active appeal process, USATF will allow any athletes to continue competing until the process is completed.”

But the prospect of Houlihan’s appearance in the trials brought immediate pushback from global track and anti-doping officials who made it clear that they believe Houlihan is ineligible because of the ban and should not compete.

By late Thursday, even U.S. Olympic officials seemed to indicate that Houlihan would be barred from the trials. “The U.S. Olympic & Paralympic Committee, together with USATF, can confirm that we will adhere to the WADA Code and any (Court of Arbitration for Sport) decisions that govern athlete participation in sanctioned events,” USOPC chief executive Sarah Hirshland said in a statement.

The confusion is based partly on the unusual way Houlihan’s case has unfolded.

During a Monday video conference announcing Houlihan’s suspension, her lawyer, Paul J. Greene, said that normally in a case like this, there would be an initial hearing before the Athletics Integrity Unit, which oversees an anti-doping program for international track and field athletes. That would be followed by an appeal to the Court of Arbitration for Sport, he said.

Houlihan’s case has unfolded differently, however. “We were right up against the Olympic trials (and) we agreed to a single hearing before CAS,” Greene said. “And so with that hearing now being over, the appeal route left is to the Swiss federal tribunal in Lausanne,” Switzerland. 

It’s not clear whether such an appeal has been filed or how long it could take. The Tokyo Games begin July 23. 

USATF’s decision to let Houlihan compete was countered sharply by other global bodies involved in overseeing track and field.

A spokesman for the World Anti-Doping Agency said Thursday afternoon it was working to confirm whether Houlihan would indeed be allowed to run “and, if so, why the USATF is saying it will let her compete despite the fact she is serving a four-year suspension for an anti-doping rule violation.”

A spokeswoman for World Athletics, track and field’s international governing body, said late Thursday: “All Member Federations must respect CAS decisions under the WADA code. We are talking to USATF.”

It wasn’t clear what would happen if Houlihan qualified for Tokyo. The International Olympic Committee didn’t respond to a request for comment. Nor did the Bowerman Track Club, the Nike-sponsored group for which Houlihan competes. 

On Jan. 14, Houlihan received a notice from the Athletics Integrity Unit that a testing sample she had provided on Dec. 15, 2020, resulted in an “adverse analytical finding” for a steroid called nandrolone and that she was provisionally suspended. Last Friday, she learned that the three-member CAS panel had rejected her explanation and handed her a four-year suspension. 

Houlihan’s defense centers on her contention that her failed test was caused by eating a tainted burrito at a food truck near her home in Beaverton, Ore., that serves pork offal, or organ meat. 

Consumption of the “edible parts of non-castrated male pigs” can trigger positive tests for nandrolone, according to a document by the World Anti-Doping Agency. Houlihan’s initial statement said the likely explanation for her failed test was “a burrito purchased and consumed approximately 10 hours before that drug test from an authentic Mexican food truck that serves pig offal.”

In a follow-up interview with The Wall Street Journal, Greene acknowledged that 

Houlihan actually ordered a carne asada, or beef, burrito, not pork, the day before her drug test. They believe Houlihan was either given the wrong order or a burrito that included pork, he said.

Write to Rachel Bachman at Rachel.Bachman@wsj.com