A federal administrative court in Switzerland has upheld the right of the family that controls Swiss construction chemicals producer Sika to sell its stake to France’s Saint-Gobain for around $2.8 billion without consulting the remaining shareholders.

The feud between Burkhard family – which through its Schenker-Winkler Holding controls Sika despite not having a majority shareholding – arose late last year. Large shareholders opposing the so-called opt-out clause allowing such a procedure are the Gates foundation trust of Microsoft founder Bill Gates and his wife, Melinda, along with Cascade.

Urs Burkhard, spokesman for the family who are related to Sika’s founder Kaspar Winkler, said the court’s decision strengthens the case for proceeding with the sale, which also has been opposed by Sika’s board of directors and employees. He added that it also strengthens the family’s “determination to succeed in carrying out an industrial project that would allow Sika and Saint-Gobain to increase their sales and profitability, thereby creating value for all their shareholders and other stakeholders involved.”

The Gates foundation trust and Cascade have said they will “continue to defend their shareholder rights and oppose the ill-advised planned transaction that was structured to serve only the interests of Schenker-Winkler Holding and Saint-Gobain.” In their view, the sale “makes no strategic sense, is an affront to good corporate governance and is not in the interest of Sika’s business, employees, customers or public bearer shareholders.”

Those opposing the deal maintain that the sale of the family-owned stake of 16%, which carries voting rights equal to 52%, would be tantamount to Saint-Gobain taking over the entire company. The French rival has offered a 78% premium for the Burkard stake but has stressed that it does not intend to bid for the rest of the company’s shares, prompting claims of unfair treatment. The family argues, however, that all investors should have been aware of the legal situation.

In December 2014, the holding unsuccessfully sought to circumvent internal opposition by removing the three directors opposing a sale, thereby prompting a lawsuit by the other shareholders. The family is now trying to have decisions taken with the votes of the three directors voided.

Due to the dispute, Saint-Gobain and the family have been forced to extend the deadline for completing the transaction from the end of 2015 to mid-2016.