Hearts have started a legal challenge against their relegation from the Scottish Premiership after clubs failed to back league reconstruction.
The Tynecastle outfit - along with Partick Thistle and Stranraer - had their demotions confirmed after only 16 SPFL clubs indicated they would support an expanded top flight.
Hearts said in a statement they were "disappointed, yet not surprised".
They have taken the "necessary steps" to start legal proceedings.
"We have stated from the beginning that the unjust and unfair treatment of Hearts, Partick Thistle, Stranraer, and indeed other clubs, cannot be allowed to go unchallenged," the statement read.
"While many weeks have been wasted in trying to find a solution, we must now formally challenge this outcome. Now that all other avenues are closed, we are left with no choice but to proceed with a legal challenge."
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The SPFL says its board has "agreed to draw a line under reconstruction talks" and the existing 12-10-10-10 set-up will remain.
That means Hearts are consigned to the Scottish Championship, Partick Thistle to League One and Stranraer to League Two.
It also means Lowland League champions Kelty Hearts and Highland League counterparts Brora Rangers will not be invited to join the SPFL.
Hearts reiterated their belief no club should be disadvantaged unnecessarily amid the Covid-19 pandemic and say the failure to avoid doing so is "an unfortunate condemnation of Scottish football".
The Edinburgh club say they must now act on behalf of their supporters, employees and sponsors.
"We cannot, and will not, sit idly by and watch the decisions made in the past few months further damage Heart of Midlothian Football Club," the statement added, addressing the fans.
"Thank you for fighting for us, now allow us to do the same for you."