The population of the world is more than three billion which is growing at the rate of more than 2% or faster than ever in any decade. Previously the world population doubled in 200 years after 1700 century, after this it doubled in 100 years and in the current period it will double in less than 35 years.
According to the Indian census 2011 the population of India was counted to be 1,210,193,422 and is the 2nd most populous country in the world after China. And a survey said that India will the most populous country in the world surpassing China by 2025.

Cause of overpopulation

● The birth rate is higher than the death rate in the country. The difference between the rates surely will make rise in the population.
● Advancement in the medical field is the biggest reason of the increasing population. Nowadays, very less person dies due to any disease compare to the previous decades. Government is providing cheap medical facilities to all the people which is affordable by all the class of people.
● Advancement in agricultural field due to which the farmers are able to grow more amounts of the crop in the same patch of land. This made them easy to feed more mouths in the same field. 
● Poverty – the families who are below the poverty line have a mental thought that if they would give birth to more number of children, they would help them in uplifting their lives and the more number of hand will increase the comfort in their old age. As compared to the present less number of children survived so they gave birth to more and more.
● Illiteracy – people have less knowledge about family planning and have less knowledge of the contraceptives and other methods to stop pregnancy. Marrying their child at early ages make them produce more children.
● Immigration – the illegal migration from different countries like Nepal, Bangladesh, and other refugee make rise in the Indian population.

Effects of overpopulation 

Unemployment- the rapid increase in population doesn't match up with the number of employment opportunities. This lead to unemployment.
Pressure on infrastructure- population growth increases the number of people living in per meter area.
Decreased production and increased cost - The production growth can't be matched up with the increased demand in between the people due to rapid population growth. So, the price of goods increases.
Inequitable income distribution - generally the lower class of people have more children. They work as labor or low post in any work. Due to this the richer become richer. In India richest 10% owns 80.7% of the wealth.
Resources utilization- The increase in population makes increase in consumption of natural resources. It unbalances nature, trees are cut to meet people's demand etc.

There should be law or not?

India is a country with 2.6% of total earth area and with 17% of world population with a limited natural resources, it is the second most populated country.
China with leading population in the world have came up with the law one children policy, in which they are allowed to have a single child, now by seeing that after a decades maximum population in China will be ageing, so, they have dropped there aggressive behaviour in that laws and has started to urge for two children who would be a part of young china.
Indian parliament is against of coming out of law regarding population growth but they have taken a path of general awareness regarding the family planning and health of children and mother. They have come up with two children policy which says “hum doo humare doo”
In 2016, a bill was introduced to President Ram Nath Kovind which talks about the population bill to be introduced in whole India which says, if in a family there will be more than two children the child after the second one will not be part of any government subsidies and policy.
From my point of view, there should be law which doesn't restrict on the no. of children but instead of this they should restrict the government benefits to the third or child born afterwards. This would be the best ways through which the government can achieve a part in control over number of children. Government should mainly aim on the awareness of two children which benefits the health of the children as well as the mother.