Matt Hancock has repeatedly refused to say whether Dominic Cummings 'did the right thing' in travelling 260 miles to Durham with his family during lockdown.
The Health Secretary is relying on the British public to do their "civic duty" and agree to self-isolate for two weeks even if they're healthy, under new 'test and trace' rules.
He confirmed people will not receive penalties for not abiding by the NHS test and trace self-isolation period "in the first instance".
He said "we are all on the same side" in the fight against coronavirus.
But asked whether the Prime Minister's aide had done so, he refused to answer.
He told the BBC: "We are instructing people to stay at home for that 14-day period."
Radio 4's Nick Robinson asked: "They can't drive? They can't go to a beauty spot?"
Mr Hancock said: "Well, the instructions are absolutely clear and they are that people should self-isolate at home for that 14-days, that's right."
Mr Robinson noted that last time Mr Hancock said things were "very clear" and an "instruction" - Mr Cummings did something "completely different."
"I think the vast majority of people will understand that it is in everybody's interest that those who are at higher risk follow these requests from the NHS, these instructions," Mr Hancock said. "And it's very, very important that they do."
Mr Hancock said: "I think as I've said before, I've answered that question and what matters..."
Mr Robinson interrupted: "Did he do the right thing? Did he do the right thing? Did he do his duty?"
Mr Hancock audibly sighed, saying: "Oh, Nick."
He went on: "I've answered this question before, a couple of days ago, and the Prime Minister's answered all of these questions endlessly."
Mr Robinson said: "No, no, he's never answered the moral case, whether he did the right thing."
Mr Hancock said: "Well I've said that he was acting within the guidelines. I also understand why reasonable people might disagree with that.
"But what matters..."
Mr Robinson interjected again: "No, no, forgive me. What matters is not dodging the question that I'm asking you. I'm asking you, using your words, Secretary of State, these are your words. You say duty, you say 'right thing', you say do your bit.
"And what people are saying to you is that Mr Cummings did none of those and whenever ministers are asked they try and dodge the question. So did he do the right thing?"
Mr Hancock said: "Far from dodging the question, Nick, I have directly answered it. Because my judgement is that as has been told in great detail in public, my view is that he followed the guidelines. I understand why some people don't agree with that, but that is my view."
