Max Moussazadeh, convicted of murder, has been in a Texas prison for 19 years after he served as a lookout during a robbery in which a partner shot and killed a man.
He filed a 2005 federal lawsuit accusing the prison system of failing to offer him kosher food, though it accommodated inmates with special dietary needs such as diabetics.
Moussazadeh's case is based on a federal prison reform law enacted in 2000 which says that a prison must have a compelling reason to impinge upon the exercise of religious freedom.
After Moussazadeh filed his suit, the Texas prison system started a kosher food program at its Stringfellow prison and transferred all Orthodox Jewish prisoners, including Moussazadeh, to that unit.
But after Moussazadeh, now 35, committed disciplinary infractions at the prison, the state transferred him to its higher-security Stiles unit, which does not provide kosher food free of charge to inmates, though it does offer prepackaged kosher meals for a fee.
A district court dismissed the case, saying Moussazadeh was "insincere" in his commitment to kosher food. The case is now before a federal appeals court in New Orleans.
"The record indicates that only about half the time did he go through the kosher kitchen line (at Stringfellow), the rest of the time he went through the regular line," said Texas Department of Criminal Justice lawyer Arthur D'Andrea at a hearing on Monday.
Judge Carolyn King questioned whether such behavior proves insincerity. Recalling a time when her own Catholic church prohibited its members from eating meat on Friday, she pointed out that some Catholics frequently violated the rule.
Following a kosher diet generally means consuming only food that has been harvested and prepared in accordance with Jewish dietary law. Adherents abstain from pork, shell fish, and mixing meat and dairy products in a single meal.
Judge Rhesa Barksdale said Moussazadeh's own behavior landed him in a higher-security unit without a kosher kitchen.
Federal prisons and the state prisons of 35 states currently provide kosher food to Jewish inmates, said Luke Goodrich, deputy general counsel at the Becket Fund for Religious Liberty, which has assisted in Moussazadeh's representation.
The Becket Fund is pursuing a similar case in Florida, and earlier this year a court ordered the Indiana Department of Corrections to provide kosher food for Jewish inmates.
The three-judge panel did not indicate when it would rule on the case, but such decisions typically take months.
Moussazadeh is to remain in prison until December 2023.