But the privacy rights group was on his side Monday when its Florida branch filed a "friend-of-court" motion on behalf of Limbaugh arguing state officials were wrong in seizing his medical records for their drug probe.
"For many people, it may seem odd that the ACLU has come to the defense of Rush Limbaugh," ACLU of Florida Executive Director Howard Simon said in a released statement.
"But we have always said that the ACLU's real client is the Bill of Rights, and we will continue to safeguard the values of equality, fairness and privacy for everyone, regardless of race, economic status or political point of view," Simon said.
The ACLU contends that state law enforcement officers violated Limbaugh's privacy rights by taking possession of his medical records as part of their criminal investigation into the commentator's alleged "doctor-shopping" to feed his prescription-drug addiction.
"While this case involves the right of Rush Limbaugh to maintain the privacy of his medical records, the precedent set in this case will impact the security of medical records and the privacy of the doctor-patient relationship of every person in Florida," Simon said in his statement.
The motion, filed with the Fourth District Court of Appeal (search), claims the state encroached upon the Florida constitution's right to privacy when law enforcement officials confiscated Limbaugh's medical files.
The ACLU said it was trying to "to vindicate every Floridian's fundamental right to privacy by ensuring that the state be required to comply" with the law.
Its motion comes a week after a judge ruled that Limbaugh's medical records were to stay out of prosecutors' hands for at least 15 days more while his lawyers worked on an appeal to permanently seal them.
Limbaugh's attorneys asked for the extension while they appealed the judge's earlier decision allowing prosecutors to examine the files for evidence that the commentator illegally purchased painkillers.
The records included "the most private conversations between doctor and patient," the radio host's lawyer, Mark Shapiro, said last week.
Investigators seized the records last month after discovering that Limbaugh received more than 2,000 painkillers, prescribed by four doctors, at a pharmacy near his Palm Beach mansion.
Limbaugh's former maid told investigators she had been supplying him prescription painkillers for years.
Limbaugh admitted his addiction to prescription painkillers in October, saying it stemmed from severe back pain. He took a five-week leave from his afternoon radio show to enter a rehabilitation program.
Prosecutors have not filed charges against Limbaugh and their investigation will be delayed until the court decides whether to keep the records sealed past the new deadline.
The radio host and his legal team have criticized Palm Beach State Attorney Barry Krischer (search), a Democrat, for opening the records and accused prosecutors of pursuing Limbaugh for political reasons.
The Associated Press contributed to this report.