Who can order for carrying out “Inspection” and under what circumstances?

As per Section 60 of MGL, Inspection can be carried
out by an officer of CGST/SGST only upon a written
authorization given by an officer of the rank of Joint
Commissioner or above. A Joint Commissioner or an officer
higher in rank can give such authorization only if he has
reasons to believe that the person concerned has done one
of the following:
i. suppressed any transaction of supply;
ii. suppressed stock of goods in hand;
iii. claimed excess input tax credit;
iv. contravened any provision of the CGST/SGST
Act to evade tax;
v. a transporter or warehouse owner has kept
goods which have escaped payment of tax or
has kept his accounts or goods in a manner that
is likely to cause evasion of tax.