When Ms Azlina Jailani wanted to get married several years ago, her life got complicated with court hearings and whispers behind her back.
The Christian convert could not register with the Registrar of Marriages because she is legally a Muslim.
In Malaysia, where a Malay is constitutionally also a Muslim, such complications are not new.
But increasingly lawyers say the country has to set clearer ground rules to govern all religious conversions.
Both Ms Azlina and her lawyer declined to be interviewed as her case is before the civil court.
She is seeking a declaration that she is free to practise the faith of her choice, and have the word 'Islam' dropped from her identity card.
The normal procedure would be to apply to the Syariah Court for approval, often a lengthy process.
Ms Azlina is trying to avoid this by falling back onto the constitutional guarantee on the freedom of religion.
Islamic and constitutional law professor Shad Faruqi told The Straits Times that there is a legitimate reason for requiring legal approval for conversions - prevent Muslims from evading the law by leaving their faith when caught for a religious offence.
Religion also carries a particular significance in Malaysia because of its implications for ethnicity, he said.
Former National Mosque imam Pirdaus Ismail said that as Islam has a special status in the Constitution, the country's laws are designed to protect the sanctity of the religion and its followers.
'However, the laws are implemented with a spirit of tolerance,' said the Umno Youth executive member.
The courts have seen several high-profile conversion cases recently. Earlier this year, a court heard a custody battle for two young children converted to Islam by their father after he became a Muslim. Their mother remained a Hindu.
The couple was awarded joint custody but daily care was given to the mother who must, however, bring the children up as Muslims.
Another recent case was that of four Muslims in Kelantan who renounced Islam after the Syariah Court ordered them to stop following deviationist teachings. They were subsequently jailed for violating this order.
Conversions from Islam, while few in number, have thrown up painful issues for Malaysia where religious differences often cause family and community rifts.
Reluctance to discuss this taboo subject has left uncertain how the constitutional guarantee of the freedom of religion applies to Muslims.
'We need the law to step in to provide clarity,' Prof Shad said.
Ms Azlina's case, to be heard by the Court of Appeal on Thursday, is seen as an opportunity for the court to shed light on the constitutional provision on religion.
'So far, there hasn't been any definitive pronouncement by the court on its application to Muslims,' said lawyer Malik Imtiaz Sarwar who represented the four defendants in the Kelantan apostasy case.
That case ended in the Federal Court without a clear indication on this issue, and he is applying for a review.