A disabled man has won a Supreme Court case after a dispute with a woman with a buggy over wheelchair space on a bus.
It means bus drivers will have to do more to accommodate wheelchair users.
Wheelchair user Doug Paulley brought his case after he was refused entry to a FirstGroup bus in 2012, when a mother with a pushchair refused to move.
First Bus said the ruling meant drivers would not have to remove customers from its vehicles, while Mr Paulley said the ruling would make "a major difference".
The court said the company should consider further steps to persuade non-wheelchair users to move, without making it a legal duty to move them.
It ruled that FirstGroup's policy of requiring a driver to simply request a non-wheelchair user to vacate the space without taking any further steps was unjustified.
However, the judgement fell short of making it a legal requirement for bus companies to compel non-wheelchair passengers to move from the space.
Welcoming the ruling, the company said bus drivers would not have to remove customers from buses, which it said was "a key issue for us".
The firm said it was pleased the Supreme Court found it did not discriminate against Mr Paulley.
Disability charity Scope said the ruling was "an important milestone".
Penny Mordaunt, the Minister for Disabled People, Work and Health, said she would be talking to the Department for Transport about "clarity, good practice and the powers of transport providers to ensure this ruling becomes a reality".
The case was triggered when Mr Paulley, from Wetherby, West Yorkshire, attempted to board a bus operated by FirstGroup which had a sign saying: "Please give up this space if needed for a wheelchair user."
Mr Paulley was left at the stop because a woman with a sleeping baby in a pushchair refused to move out of the designated area when asked by the bus driver. She said the buggy would not fold.
He had argued FirstGroup's "requesting, not requiring" policy was discriminatory.
Reacting to the judgement, Mr Paulley told the BBC: "Who would have thought that five years on I would still being discussing the day I had that problem going across to see my parents for lunch?"
By Clive Coleman, legal affairs correspondent
Today's ruling falls short of finding that bus companies can remove non-wheelchair users from the bus, but makes it clear they must do more than simply request they move from the wheelchair place.
Where a driver concludes a refusal to move is unreasonable, he or she should consider some further steps to pressurise the non-wheelchair user to vacate the space.
These might include rephrasing the request as a requirement, or even a refusal to drive on for several minutes "with a view to pressurising or shaming the recalcitrant non-wheelchair user to move".
This places a lot of responsibility on the driver.
There are also major implications for all service providers with wheelchair spaces or facilities - supermarket car parks, disabled toilets on trains etc.
Companies will have to make sure their policies go far enough to avoid substantial disadvantage to wheelchair users, and that staff are properly trained to enforce them.
He added: "It's been amazing the amount of support I've had - disabled people, organisations, lawyers, family, allies. This is hopefully going to make a major difference to disabled people's travel."
Asked whether the verdict went far enough, Mr Paulley said the issue would always involve "a matter of judgement" from drivers.
He added: "There's always got to be some judgement and there will always be some exceptional circumstances where somebody can't be expected to move out of the space.
"But what this judgement means is the driver has to make their own decision as to whether the person is being unreasonable in refusing to move, and if they are, he or she has to tell them that they are required to move, and if necessary refuse to move the bus until they shift.
"So that's very clear, I think."
However, Mr Paulley's solicitor, Chris Fry, said the ruling had fallen short.
"The judgement should have gone further - there's no right as things currently stand to force someone off a bus. So it goes as far as that, but not that far yet."
Mr Paulley won an initial case against FirstGroup in 2013, after he argued its policy of "requesting, not requiring" able-bodied passengers to move was unlawful disability discrimination.
However, FirstGroup successfully appealed in the Court of Appeal in 2014, after which Mr Paulley brought his case to the Supreme Court.
The Equality and Human Rights Commission, which supported Mr Paulley at the Court of Appeal and the Supreme Court, described the latest decision in the case as "a victory for disabled people's rights".
Speaking on BBC Two's Victoria Derbyshire Programme, wheelchair users reacted to the judgement.
Zoe Hallam said: "I think the whole point of the case was to try to get more clarity about how far bus drivers are meant to go in terms of requiring people to move out of the space. I'm not sure this ruling has provided this clarity."
Will Pike told the programme: "We were seeking some sort of clarity.
"Doug has done an incredible job of bringing this issue to light and to the mainstream media's attention, and at the end of it there's no news.
"It's kind of back to square one."