Under the Paris Convention, an application should be filed in India within 12 months from the date of the basic application filed in the home country of the applicant.
For national phase entry under the Patent Cooperation Treaty (PCT)- as against the minimum period of 30 months prescribed by the PCT- the Indian law allows 31 months to enter into National Phase from the earliest priority date. Amendments made to the international application in response to the Search Report or Preliminary Examination Report can be considered as amendments made to the patent's specifications at the option of the applicant(s).
All applications are published after 18 months of the priority date or filing date of the application whichever is earlier. In case of national phase applications under the PCT, they are published immediately after filing, as 18 months from the priority date would have been generally over. An applicant can request for an early publication too.
A request for examination has to be filed within 48 months from the date of priority.  Patent applications are examined in the order of filing request for examination with respect to compliance with the formalities and patentability requirements. Novelty is not limited to India. A novelty examination generally takes into consideration any specification previously lodged with the Patent Office, any patent previously granted in various countries and any other materials an examiner treats as relevant. The Patent Office may ask to make amendments that it deems necessary to conform to the requirements. 

An applicant has to put the application in order for acceptance removing all the objections within 12 months from the date of the First Examination Report. There is no provision for extension of time under any circumstance. Once an application is accepted, it would be granted a patent and published in the Official Journal of the Patent Office. 

There are provisions for both pre-grant and post-grant opposition. In case of pre-grant opposition, after publication but before grant, any person may file a representation by way of opposition with the Controller of Patents on the ground of patentability including novelty, inventive step and industrial applicability or non-disclosure or wrongful mentioning of source and geographical origin of biological material used in the invention in complete specification, and anticipation of invention by the knowledge, oral or otherwise, available within any local or indigenous community in India or elsewhere. Rights of an opponent are limited here as the law prescribes that an opponent shall not become a party to any such proceedings only for the reason that he has made such representation. 

Post-grant opposition is elaborate. Any interested person may give a notice of opposition within one year from the date of publication of the grant of the patent. In addition to the grounds mentioned above in pre-grant opposition, post-grant opposition can be on the grounds of prior use in India, insufficient explanation of the invention or the method of manufacture, application in India after the prescribed period for claiming priority, etc. The Controller constitutes an Opposition Board to decide the matter after going through the materials furnished by both parties and statements made during the hearing, if any.  

A patent is valid for 20 years from the date of filing the application. In case of national phase applications under the PCT, international application date is treated as the date of the application. Though convention applications get priority under the Paris Convention, for such applications, the 20-year period commences from the date of application in India.
A patent will remain valid subject to the payment of the prescribed annuity (annual fees). The annuity is to be paid only after the issuance of the patent. 
The right to a patent may be assigned, licensed or transferred through succession. The assignment of patent applications or granted patents must be made in writing. 

Working of patents is an official requirement in India. In case the owner or the licensee(s) of a patented invention fails to satisfy the stipulated working requirements of the country within 3 years as of the date of grant, the patent will be subject to compulsory licensing under the provisions of the law.
The rights conferred by a patent on the registered patentee expire on the lapse of the protection period as prescribed by the law, lawful assignment of the patent rights, final court decision to this effect or nonpayment of the annuity fees.

In a suit for infringement, a court may grant an injunction and damages or an account of profits.
 The Indian Patents Act, 1970 was amended in 2014 with effect from February 28, 2014. The official amendments can be downloaded from this link. The main highlights are as follows:
1. A new category of applicant in the form of  “small entity”. Thus, the applicants are classified as – individual, small entity and other entity.
2. The official fee of “small entity” is half of the official fee for an “other entity”. 
3. A new Form 28 is to be submitted to claim the benefits associated with the applicant’s status of  “small entity”.
4. The official fee is doubled.
5. 10% surcharge on official fee for documents which are not filed electronically.
6. A new Form 7A for filing of pre-grant opposition.
How to determine whether an applicant is a small entity or other entity?
a. When the applicant is engaged in the manufacture or production of goods, where the investment in plant and machinery does not exceed INR10 million ($1,626,016), the applicant will be considered as a Small Entity.
b. When the applicant is engaged in rendering services, where the investment in equipment does not exceed INR5 million ($813,008), the applicant will be considered as a Small Entity.
c. When the applicant is engaged in the manufacture or production of goods where the investment in plant and machinery exceeds INR10 million ($1,626,016), the applicant will be considered as an Other Entity.
d. When the applicant is engaged in rendering services, where the investment in equipment exceeds INR5 million ($813,008), the applicant will be considered as an Other Entity.
e. When we claim Small Entity status, we need to submit proper documents to establish the status.
For claiming the status of small entity, we must file Form 28 along with the relevant documents at the Indian Patent Office. If the applicant is a “small entity”, the supporting documents must be provided to establish the status of the applicant.