HUNTSVILLE, Texas — More than a year after a judge ordered Texas to divulge the source of its execution drugs, the information has not been released, legislators passed a state law protecting the prison agency from doing so, and the lengthy appeal that has allowed the provider to remain secret will finally be heard.

Texas, the nation’s most active capital punishment state, will try to persuade an appeals court Wednesday to keep the Texas Department of Criminal Justice from being forced to disclose who provided the lethal drugs before last Sept. 1, when the law shielding suppliers took effect.

Prison agency spokesman Jason Clark wouldn’t say Tuesday whether the provider of execution drugs then is still the supplier, reiterating that the drugs come from a licensed compounding pharmacy that is not publicly identified. Such pharmacies custom-make drugs for a specific client, although critics contend they operate with less stringent regulatory scrutiny and testing standards compared with larger drug companies.

The availability of execution drugs has become an issue in many death penalty states, and Texas began using a compounding pharmacy as its source when traditional pharmaceutical makers refused to sell their products to prison agencies to be used for capital punishment. Similar lawsuits about whether states must identify their providers have been argued in states including Georgia, Arkansas, and Missouri.

Lawyers for the two inmates originally named as plaintiffs in the Texas suit failed to block their executions in April 2014 with arguments that the identity of the supplier of the sedative pentobarbital was essential to verify the product’s potency so it didn’t cause unconstitutional pain. Their suit, filed under the Texas Public Information Act and now before the Austin-based Third Texas Court of Appeals, argues that changes in execution methods and drugs from ‘‘new and unreliable sources’’ led to botched executions in Oklahoma, Ohio, and Arizona.

Associated Press