The sisters, both in their eighties, feel they should be exempt from inheritance tax when once of them dies -- just like married couples and registered same-sex partners are under British law.

Joyce and Sybil never married.  They jointly own the family home they have lived in all of their lives.

When one of them dies, the government will impose a hefty inheritance tax on the survivor.  The tax is so substantial that it might force the survivor to sell the home in order to raise the necessary funds.

The British government provides no method for siblings to gain a tax exemption, no matter how interdependent they are or how long they have lived together.  Close relatives are prohibited from entering into a civil partnership or marriage.

The sisters wrote to the British Chancellor before every Budget since 1976 asking for exemption for family members from inheritance tax. 

Two years ago, Joyce and Sybil also wrote to the European Court of Human Rights.  They were surprised when the court agreed to hear their case.

The sisters found a lawyer to represent them.  He argued that the tax is discriminatory and violates the sisters' rights under the Human Rights Convention of the European Union. 

After all, he pointed out, a surviving party in a marriage or a civil partnership would pay no tax at all.  In contrast, Joyce or Sybil might have to sell their home in order to pay the tax after one of them dies.

Last year, a divided panel of judges ruled against them in a 4 to 3 vote.

Reacting to the court's decision, Joyce Burden told a British newspaper, "If we were lesbians, we would have all the rights in the world. But we are sisters, and it seems we have no rights at all."

So the sisters filed an appeal, asking for a rehearing by the court's Grand Chamber.  A panel of 17 judges, from 17 different nations, heard the case on September 12.  A decision may be handed down as early as December.

The lawyer representing the Burden sisters argued that the Civil Partnership Act of 2004 infringes on their right to own property and their right to be free from discrimination under the region's Human Rights Convention.  Their relationship is more solid and longer lasting than most same-sex partnerships and yet, solely because they are blood related, the sisters are prevented from registering as civil partners.

An attempt to extend the exemption to close relatives who had lived together as adults for at least 12 years was overturned by the House of Commons when the Civil Partnership Bill was in debate.

The sisters are understandably angry.  Joyce told a British newspaper that she would rather burn down the house than to have to sell it to pay taxes to the British government.

"If Gordon Brown wants it that much he can have the ashes," she said.  "We are both very angry and are not going to let Mr. Brown have one pence."

"They have taxed us all our lives," Joyce added, "and we have never claimed any benefits, apart from our pensions which we paid into."

Sybil also had a few choice words to say.

"We are looked down upon for being single," she told The Times.  "We just want to be treated as equal citizens and given the rights we deserve."

Sybil pointed out that she and Joyce "saved the Government thousands by caring for our elderly sick relatives till they passed away and have never claimed a penny apart from the pension."

If they lose their case before the 17-member court, the battle will turn from legal to political. 

"The whole issue of inheritance tax needs to be revisited so that relationships outside of marriage or civil partnership are recognized," said Neil Parish, a conservative member of Parliament. "Inheritance tax should only apply if property is passed down from one generation to the next, not between the same generation.

"Sybil and Joyce Burden deserve to have their 80 year partnership as sisters recognized by the law," he added. "I will lobby the government to change this grossly unfair law."