What are the criticisms of the Kantian ethics system?

What will be an ideal response?

The criticisms of Kant's ethics system include both those that pertain to deontological systems in general and those specific to his system. The fundamental criticism of deontological systems is that they fail to explain why a principle or right should be respected. When one attempts to do so, one is often led to justifying it in terms of the extent to which it protects or promotes human interests.
More specific criticisms of rights-based ethics systems are that they may not (1 ) identify sufficiently precisely where the corresponding duty lies, (2 ) indicate priority when one right conflicts with another, and (3 ) indicate when—if ever—it would be acceptable to violate a right.
With respect to the first criticism, every right is accompanied by an associated duty, but who is to bear the burden of that duty is not always clear. Some negative rights, such as the right of free speech, impose a duty on everyone not to interfere with that speech. In the case of a claimed positive right, such as a right to medical care, however, the duty may fall on the individual, family, employer, or government. In such situations, legislation is often required to clarify where the duty lies. Legislation, however, reflects interests, and hence preferences and consequences.
A second criticism is that Kant's system does not clearly indicate whether or when one right has priority over another. The categorical imperative requires that individuals be treated as autonomous and so always as an end and never solely as a means. Kant's view was that there would be no conflict among the rights consistent with the categorical imperative. When a person, however, attempts to articulate the set of intrinsic rights, conflicts frequently appear. In such a case, Kant would argue that the person should reexamine those rights from the perspective of the categorical imperative, eliminating those inconsistent with it.
A third criticism centers on whether there are any circumstances in which it would be acceptable to violate a maxim or right. For example, if rights are in conflict, it may be necessary to violate one to respect another. A violation of a right for whatever reason is a moral wrong, but the seriousness of the violation must be considered. In the language of justice theory, the issue is when it is acceptable to violate one right to avoid a violation of a more important right.
In spite of these criticisms, individual rights are a fundamental component of our ethical intuition. Rights are embedded in constitutions, statutes, and moral understandings. The duties corresponding to legal and moral rights provide fundamental constraints on the actions of managers and on the policies and practices of firms.
The practical difficulties with the application of rights-based ethics systems pertain to the evaluation of claims about rights, the priority of various rights, and the relationship between rights and other concerns such as well-being and justice.