Judges and couples should be told what they are aiming to achieve with any financial settlement after a divorce, the body that recommends law reform has said.
It is time to decide whether separating partners should be compensated for sacrifices they have made in a relationship or simply encouraged to achieve independence, it said.
The law in England and Wales is unclear and treats a family court judge like a bus driver who has been told how to drive and told that he must drive, but has not been told where to go, nor why he is to go there, the Law Commission said.
At the moment, the law enables the court to make financial orders and asks judges to consider the length of a relationship, parties' resources and responsibilities, however it doesn't say what the judge is meant to achieve
But Professor Elizabeth Cooke, the law commissioner leading the project, said she is approaching the idea of artificially limiting support, as in Scotland where there is a strong preference for it not to last beyond three years, with "great caution".
She said: "We think that could cause unwarranted hardship. The Scottish system has a reputation of being harsh to women.
"Among the most painful of human experiences is the ending of a relationship. Divorce or dissolution of a civil partnership is a miserable experience for all involved. The law can make that misery worse if the law fails to be clear and transparent or accessible.
"If the law isn't clear, it contributes to acrimony and wasted costs."
While the law enables the court to make financial orders and asks judges to consider sensible factors such as the length of a relationship, parties' resources and responsibilities, "what it doesn't do is say what the court is to achieve", Prof Cooke said.
"That's what makes the law so difficult to explain and encapsulate. It would be far clearer if the law was to state what is to be achieved.
"Is it trying to compensate people for what they have lost as a result of the marriage, for example earning capacity? Is it trying to move away from what might have been and to think about how long it will take for them to achieve independence?
"And how far should the law be incentivising independence, trying to encourage people to move on?"
A consultation over the issue, which closes on December 11, also considers whether a formulaic calculation should be used to determine a settlement, as in Canada.
"We haven't made a proposal in the consultation paper because we felt on this issue it was very important to have an open paper to discuss the options and set out some of the reasoning, some of the experiences of other jurisdictions," Prof Cooke said.
"They raise different demands. If you're trying to compensate, you have to do a bit of crystal ball gazing: where would this person be without everything that happened?
"If you're trying to support a transition to independence, you're not really looking at what might have beens, you're looking at the future and what can be achieved."
But any reform of this area of the law is still years away. A report next autumn will recommend further research and pilot projects before any changes are made.
The consultation also considers what should happen to property that one of the partners owned before the relationship, or inherited during it.
Prof Cooke said the commission is "looking at the boundaries of the sharing principle" and asking whether there was anything that is not shared at the end of a relationship.
Moves to reform the law come after the highest court in the land allowed an appeal last November by hairdresser Patricia Jones against an earlier ruling that ice cream salesman Leonard Kernott was entitled to half of the value of the house they shared nearly 20 years ago in Thundersley, Essex.
The five Supreme Court justices said Ms Jones was entitled to 90% and Mr Kernott, of Benfleet, Essex, should get 10% at the end a fight which started in 2008 and had seen lawyers argue in a county court, the High Court, the Court of Appeal and the Supreme Court.
It also follows last year's consultation on whether to make pre-nuptial deals legally binding.