The Supreme Court ruling closes a loophole in Sec. 375 of "The Child Marriage Restraint Act" (passed way back in 1929) which people used to exploit the law.

1. For this law to be effective, like other laws, it requires society's vigilance. Report a case of child marriage whenever you come across it.

2. Child marriage sitiation in other countries: In the UK the legal age for marriage and consent is 16, who still count as minors. 

In the United States, more than 200,000 children married in US over the last 15 years, often using some legal loophole. 
In June 2017, New York banned children aged under 17 from marrying. Previously minors as young as 14 were allowed to wed under state law providing they obtained parental and court permission.

3. When will India have a Public sex offenders list?