Just one stumbling block for one migrant? Or something much more serious which threatens the government's approach to small boats?

Those are the questions being posed in government now after a 25-year-old Eritrean man managed to block the government from putting him on a flight to France at the High Court on Tuesday.

It is just a temporary decision. The judge granted a pause of at least 14 days so the man, who is not being named for legal reasons and arrived in the UK on a small boat last month, could provide evidence of his claim that he has been a victim of modern day slavery.

But it is certainly frustrating for a government which had hoped that the removal flights to France under the 'one in, one out' scheme would begin this week.

They may still do so. Either way, the steady drumbeat of people being put on flights through the week appears not to have materialised.

The stumbling blocks with Tuesday's case show how complicated quick turn-around deportation or removal plans can be.

And in this case, they concern the UK's laws on modern day slavery and trafficking - and the way the Home Office handles these cases.

After the man arrived on a small boat in August, officials swiftly rejected his case and told him he could and should have claimed asylum in France.

But he also asked for protection as a victim of modern day slavery, saying he has suffered harm in Libya, long before he came to the UK.

There was no evidence he was trafficked across the Channel, not least because his mother had paid smugglers about £1,000 to take him.

Now, here's the important twist.

The Home Office's trafficking assessors - different officials to the team organising removal flights - said the Eritrean man's story was weak.

But that rejection was not their final decision. The UK's rules allow a rejected applicant to ask for a reconsideration.

The senior judge dealing with the case repeatedly asked the man's lawyers why he could not make those representations from France, including gathering any medical evidence.

It looked and sounded like the Home Office was going to win.

But then, as the courtroom battle dragged on, the department's own trafficking officials effectively confirmed that they would not expect the man to do that.

That fatally undermined any hope the home secretary had of getting this 25-year-old on the 9am flight from London Heathrow.

If the Home Office wasn't such a secure bomb-proof building, we might have been able to hear howls from its ministerial corridors echo around the Royal Courts of Justice, two miles away.

So where does this decision leave the project?

This single decision does not kill the France returns plan, but it's symptomatic of a decades-long criticism, that the Home Office regularly snatches defeat from the jaws of victory thanks to epic levels of dysfunction.

Yes, the government never committed publicly to flights in the air this week. But in private, there was a strong expectation from those around Shabana Mahmood, the new home secretary, of a string of departures this week.

But immigration is complicated - really complicated - and the awkwardness of Tuesday's injunction aside, officials know other English Channel crossers may mount similar arguments.

The government's own KC argued in court that if the judge blocked this removal, as he went on to do, then "the deterrent effect of this policy will be undermined".

Anyone who presents a reasonable argument that they might have been a victim of trafficking is entitled to at least 45 days to "recover and reflect" - with a final decision on their case maybe a year down the road.

If this claimant gets that positive decision, he could be off the removal list for a year on top of that as he waits a final outcome.

The political risk for the government is that their own lawyer is now proved right, not least because so many arriving on small boats have travelled through countries like Libya where trafficking and abuse are rife.

It is too soon to say conclusively whether Tuesday's interim judgment means that this scheme will get bogged down in repeated legal action like the Conservatives' proposed Rwanda policy, which never got off the ground before being cancelled by Sir Keir Starmer 14 months ago when he entered office.

The Conservatives, though, see vindication in the development. Their leader, Kemi Badenoch, told LBC that her message for the government was: "We told you so."

Science Secretary Liz Kendall told BBC Breakfast that scheme was not intended as a "silver bullet" and this single ruling would "not stop this really important deal from going ahead".

The deal with France was seen by the previous home secretary, Yvette Cooper, as one of her landmark policy achievements, it is now the job of her successor, Mahmood, to make it work.

Mahmood is seen at the government as a punchier communicator - displayed, perhaps, in her opening vow as home secretary to do "whatever it takes" to tackle illegal immigration.

Her colleagues will be hoping she is not having to deploy those communication skills at the end of the week to explain why no-one has been flown to France yet.