Were the group sent to bring Harry to headquarters authorized by the Ministry in the Order of the Phoenix?

Question

In the Order of the Phoenix, a group of Order members bring Harry from the Dursleys’ to Grimmauld Place. Were they authorized by the Ministry to do so, or were they acting behind the Ministry’s back?

Answer 1

It’s unlikely - the Ministry was effectively at war with Dumbledore.

The Order of the Phoenix is a secret society founded and led by Dumbledore - it was clearly his.

“Is anyone going to bother telling me what the Order of the Phoenix –?’

‘It’s a secret society,’ said Hermione quickly. ‘Dumbledore’s in charge, he founded it. It’s the people who fought against You-Know-Who last time.”
_{^{- Harry Potter and the Order of the Phoenix, Chapter 4 (Number Twelve, Grimmauld Place)}}

At the time Harry was retrieved from the Dursleys, Dumbledore and the Ministry were at war. Fudge had said any Ministry employees shouldn’t be in contact with Dumbledore, or they’d be fired.

“Well, apparently Fudge has been storming round the Ministry checking that nobody’s having any contact with Dumbledore,’ said George.

‘Dumbledore’s name is mud with the Ministry these days, see,’ said Fred. ‘They all think he’s just making trouble saying You-Know-Who’s back.’

‘Dad says Fudge has made it clear that anyone who’s in league with Dumbledore can clear out their desks,’ said George.”
_{^{- Harry Potter and the Order of the Phoenix, Chapter 4 (Number Twelve, Grimmauld Place)}}

The Ministry wanted both Dumbledore and Harry discredited, since Fudge was trying to deny that the Dark Lord had returned because he didn’t want to face that possibility himself.

“How can he think that?’ said Harry angrily. ‘How can he think Dumbledore would just make it all up – that I’d make it all up?’

‘Because accepting that Voldemort’s back would mean trouble like the Ministry hasn’t had to cope with for nearly fourteen years,’ said Sirius bitterly. ‘Fudge just can’t bring himself to face it. It’s so much more comfortable to convince himself Dumbledore’s lying to destabilise him.”
_{^{- Harry Potter and the Order of the Phoenix, Chapter 5 (The Order of the Phoenix)}}

Fudge wasn’t in favor of Harry then either- he was glad for an opportunity to expel him.

“What Cornelius doesn’t know won’t hurt him,’ said Umbridge, who was now panting slightly as she pointed her wand at different parts of Harry’s body in turn, apparently trying to decide where it would hurt most. ‘He never knew I ordered Dementors to go after Potter last summer, but he was delighted to be given the chance to expel him, all the same.”
_{^{- Harry Potter and the Order of the Phoenix, Chapter 32 (Out of the Fire)}}

So, the Ministry almost certainly didn’t approve of the mission to retrieve Harry from the Dursleys.

Answer 2

It seems pretty clear that they were not authorized

When Harry asks the Advance Guard how they will be traveling, he gets the following response:

"Brooms," said Lupin. "Only way. You're too young to Apparate, they'll be watching the Floo Network, and it's more than our life's worth to set up an unauthorized Portkey.

If the Ministry had authorized the retrieval then they could have easily authorized a Portkey as well. Moreover, there would be no fear of using the Floo Network — who cares if the Ministry's watching it if the Ministry itself authorized the retrieval?