Nottinghamshire Police arrived at an address in Mansfield to find people from five different households mixing together.
Such a mixture is banned under restrictions introduced to combat the second wave of COVID-19.
In September, after the rule of six was introduced, Boris Johnson said members of the public should not report neighbors who break it unless they have “Animal House” evenings with “whirlpools and so on”.
In a statement, police said when the owner was asked for contact details, he refused.
When officers attempted to explain the law, he reportedly replied “that he does not believe in the COVID-19 legislation” and “continued to obstruct”.
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The 32-year-old was reported on a summons to a lower court, while six people from the party were dispersed.
Deputy Chief Constable Steve Cooper said, “I find it quite astonishing that anyone thinks it is okay to behave in this way when clear guidelines have been given not to mix up households.
“We are still in lockdown as a nation and we must continue to abide by these laws.
“COVID is real and has the potential to kill people and we cannot forget it. Everyone must do their part to limit the spread of the virus and keep people safe.
“Our approach has always been to engage, explain and encourage people to act responsibly, but we will not hesitate to resort to law enforcement action when necessary as we continue to do whatever we can to protect our communities.
In another incident, a homeowner received a fixed penalty notice after police came across a party attended by 17 people from different households in Mansfield in the early hours of Tuesday.
The latest NHS data showed the Sherwood Forest Hospitals NHS Trust, which runs King’s Mill Hospital in Mansfield, had 92 COVID-positive patients in their beds last week, including 12 on ventilators.