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.
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.
The uncertainty can make a couple's misery worse and it is time to decide whether parting spouses should be compensated for sacrifices they have made in a relationship or simply encouraged to achieve independence, it said.
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."
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.