The Germany international committed himself to Dortmund until 2031 in April, but the new agreement contained a provision that could have allowed a small group of European clubs to sign him for a predetermined fee.
According to reports at the time, the clause was valued between €50 million and €60 million and was available to only three clubs, including Real Madrid and Liverpool. However, Sky Germany has confirmed that the provision expired on 15 July, meaning neither club can now activate it.
That development is significant for Borussia Dortmund, who had faced the possibility of losing one of their most important defenders for a relatively controlled fee. The club now have greater negotiating power should interest emerge from abroad.
Real Madrid had previously been linked with Schlotterbeck, while Liverpool were also monitoring the centre-back as they considered their longer-term defensive options. The German's profile makes him an attractive target for clubs looking to strengthen at the heart of their defence.
Liverpool have been particularly conscious of the need to plan for the future, with Virgil van Dijk approaching the later stages of his career. Real Madrid, meanwhile, have also been assessing potential reinforcements in central defence.
Schlotterbeck's contract extension had appeared to offer Dortmund long-term security, although the release clause meant there was still a possible route out for a select group of clubs. That route has now closed.
The defender was 26 when he signed the new agreement, which runs until June 2031. His importance to Dortmund was evident again in their narrow 2-1 victory over Elversberg, when his defensive contribution helped the side protect their advantage.
The club can now approach any future negotiations from a stronger position. An interested team would need to agree a transfer fee directly with Dortmund rather than rely on the expired clause.
That does not guarantee Schlotterbeck will remain at the club throughout his contract, particularly if one of Europe's leading sides makes a substantial offer. However, the expiry of the provision removes the possibility of a pre-agreed exit at the reported €50m-€60m level.
For Dortmund, it is an important change to the situation surrounding their defensive leader. Any club hoping to prise him away will now have to negotiate on the German side's terms.