The amendment violated the constitutional right of religious and linguistic minorities to administer their own educational institutions, the petitions claimed.
"All the writ petitions in this bunch are dismissed," a division bench headed by Chief Justice Sunita Agarwal said. The detailed judgement was not available yet.
The amended Act gave the state education board powers to lay down qualifications and method of selection for recruiting teaching and non-teaching staff of private secondary and higher secondary schools.
It was "unjustified and unlawful," claimed the petitions filed by schools run by educational institutions of minority communities.
In the garb of regulating power, the state transgressed on the rights of the minorities and violated Articles 29 and 30 of the Constitution, they argued.
While Article 29 protects cultural and educational rights of minorities, Article 30 confers on them the right to "establish and administer educational institutions".
The state government defended the amendment, contending that it aimed to ensure a fair and transparent merit-based selection process.
The amended Act lays down the conditions of appointment, promotion and termination of employment of principal, teaching and non-teaching staff at such schools.
It also allows the Gujarat State School Service Commission to select teachers and headmasters of government-aided private secondary and higher secondary schools.
