The government consultation on high speed rail closes tonight, but the Crofton campaign group - against the current HS2 plans - have said they will continue to stand up against the alternative M18 Eastern route.
Coordinator of Yorkshire Against HS2 Jonathan Pile says they plan to submit a judicial review.
He said: "We have tried to engage with the Department for Transport and HS2 Limited and we have had it thrown back in our face, certainly by HS2 Limited.
"So, it has to go to court. We will sit down in front of diggers when it comes down to it because there is no way these plans will stand as they are."
The government says a high speed rail stop at Meadowhall is still on the table.