The first thing the police officer needs to show to you before entering your property is a "Seach Warrant" under section 93 of the CrPC. A search warrant can be issued by a district magistrate/sub-divisional magistrate/ Magistrate (First Class).
However, the police can apply section 165 of the CrPC which lets them search a premise without any search warrant. The grounds under section 165 of the CrPC are as follows:
"Whenever an officer in charge of a police station or a police officer making an investigation has a reasonable grounds to believe that anything necessary for the purpose of an investigation into any offense which he is authorized to investigate may be found in any place and that thing cannot in his opinion be obtained without undue delay without a search, such officer may search for such thing in any place within the limits of such station."
Remedies against a search warrant
1. Instituting a writ petition under Article 226 of the Constitution for quashing an illegal search warrant and for return of the seized thing/document.
2. An order under Section 93 can be set aside under 401 of CrPC in revision if it can be shown that the Magistrate had not applied its mind judicially.
3. A search carried out in contravention of law constitutes an actionable trespass and a suit for damages can be filed against the person executing the illegal warrant.
Let us know if you have any further query