Blogger and journalist Mohammad Abdul-Kader Al-Jassem, a staunch critic of the government, was detained on May 11 after a complaint against him was issued by the office of Kuwait's Emir Sheikh Sabah Al-Ahmad Al-Sabah.
He will be freed in the coming hours after posting a bail of 2,000 dinars ($6,861), lawyer Jasser Al-Jidei said, adding his client faces up to 18 years in prison if convicted.
"A medical report (submitted to the court) said he was not in good health," Jidei said, without elaborating. Jassem is known to have heart problems. He went on hunger strike after he was arrested but ended it over health concerns.
Kuwait has the freest press among Gulf Arab states but its ruler is protected from criticism by the Constitution. Many writers have been fined or imprisoned for defamation.
On his website, the blogger criticized the ruling Al-Sabah family and accused Prime Minister Sheikh Nasser Al-Mohammad Al-Sabah of mismanagement and corruption.
In April, Jassem was sentenced to six months in prison for defaming the prime minister, a ruling he is appealing, and he faces two other cases in courts.
Washington voiced concern about Jassem's case and raised the matter with Kuwait, whose foreign minister was later quoted as saying the US comments amounted to interference in Kuwaiti affairs.
Last week, the New York-based Committee to Protect Journalists called on Kuwait's ruler to intervene for his release, urging the emir to "acknowledge that critical writing such as Jassem's has an established place in Kuwaiti society and should not be criminalized."
Jassem, who has written several books on Kuwaiti politics, is also accused of spreading false news that could harm Kuwait's interests. He denies all charges.
The court has banned media in Kuwait from publishing reports about the case.
