Neymar's world-record move from Barcelona to Paris Saint-Germain this week has again brought much debate about the role of "release clauses" in Spanish and European football.
Thursday was possibly the most dramatic day in release-clause history, as La Liga's officials refused to accept €222 million when Neymar's lawyer showed up at their offices in Madrid early in the morning, only for Barcelona to reluctantly accepted the payment at the Camp Nou later in the day.
Previous Spanish transfer windows have also brought similar drama, with Manchester United failing to trigger the clause of then-Athletic Bilbao player Ander Herrera in 2013 and Florentino Perez fulfilling his election promise in 2000 by taking Luis Figo from Barcelona.
Release clauses often appear in transfer speculation stories but sometimes it can seem that even those involved in the potential moves do not understand exactly how the system is supposed to work.
ESPN FC spoke to Juan Antonio Sanchez-Bote Corzo, founder of Madrid-based Legal Sport & Asesores, to find out what clubs, players, national federations and governing bodies can or cannot do in these situations.
Where did the idea of release clauses come from and do they have any basis in Spanish law?
Sanchez-Bote: A footballer has the same legal right as any other worker to leave for a better or better paid job. The basis for release clauses in Spanish labor law is found within Royal Decree 1006 from 1985: A player who wishes to rescind his contract in a unilateral manner must compensate his club by the payment of a set sum, which is either decided by a tribunal or previously established in the signed contract. The player is then free to sign for another club.
Does the player need to have the money himself?
Sanchez-Bote: The player can deposit the agreed amount to free himself. Although in practice, and in the Neymar case, the usual thing is that the club that wishes to sign him provides the money to compensate his former club.
How is the value of the clause decided?
Sanchez-Bote: The law states that release clauses should be proportional to the salary of the player. The value should be clearly stated in the contract signed by both sides, the player and the club, and be freely agreed by both sides.
Can a player do anything if he feels the clause in his contract is too high and prohibits his freedom of movement?
Sanchez-Bote: Release clauses established with excessively high values can lead to an unequal contract benefiting the club and disadvantaging the player. This can provoke disagreements between the player and the club. If not proportional to the player's salary, it can be challenged under the law.
Sometimes reports claim that a player can have two release clauses. For example, the value might be higher if the buying club is a direct rival or from another league.
Sanchez-Bote: Once the player deposits the agreed sum to free himself, he can then sign for any other club, whether Spanish or foreign. There is no justification in the law for a contract having different clauses depending on which club wishes to sign the player.
Do clubs sometimes prefer to deal directly between themselves, to avoid any tax implications from triggering a release clause?
Sanchez-Bote: Since 2016, these type of operations are not liable for tax. You must look at what the player receives from his new club [to trigger the clause], and the indemnity payment which is made to the old club. The income and the expenditure balance out.
Were La Liga's authorities within their rights to reject Neymar's initial attempt to pay his release clause on Thursday morning?
Sanchez-Bote: The issue of the LFP not accepting the payment of the clause is a tricky one and open to different interpretations. We understand that you cannot deny a professional footballer, who in the end has the same rights as any other worker, the right to decide where he wants to play. And you also need to compensate his club with the indemnity value agreed by both sides in his contract. From our point of view, in the Neymar case the LFP should have accepted the payment of the player's clause.
What about the argument put forward by league president Javier Tebas that PSG were breaking Financial Fair Play regulations and, therefore, his association was not obligated to take their money?
Sanchez-Bote: It is true that all clubs must be in accordance with Financial Fair Play established by UEFA, but this is another question which needs to be considered on its own.
Tebas has also suggested that it was unfair of PSG to "take advantage" of a release-clause system that exists in Spanish law (but not French law) and should only be available to other Spanish clubs.
Sanchez-Bote: A clear harmonisation regarding release clauses is required around Europe, to avoid these type of problems. Our view is that UEFA should take charge of this, so that issues around release clauses are regulated on a European level.