[FONT="Times New Roman"][SIZE="7"]Respected seniors,
I hope you all would give your precious thoughts about above two subjects especially those who have prepared and appeared in the CSS exam.
As I have to opt only one of the above two subjects so according to your analysis and opinion what should you suggest me and why?
Please reply must and your precious response shall be highly encouraged.
Thanks!

I have done bachelors in law i'll suggest you to opt for International law. It overlaps with IR too. As far as criminal law is concerned you'd have to do alot more cramming for it e.g section and caselaws for punishments and imprisonment. They are so confusing.
I will also suggest to go through the given syllabus of both subjects it will give you an idea
Best of luck

Both are scoring. CE-16 shows that students who had prepared well have got excellent marks and some have even scored above 90. On the other hand both were disaster for candidates who took them lightly and did not prepare well. Many have failed the subject with poor marks. So, scoring trend is high for both subjects if one prepares excellently.
Now after analyzing scoring trend which is pretty much same for both, candidate must consider his or her aptitude for subjects. Some people perform better in theory subjects while some in numerical subjects. Some can tackle law subjects and some cannot. I advise you to go through detailed contents of syllabus and choose the subject which appeals you. It will give you idea that which subject you can prepare easily. Your interest in subject matter is very important.
While choosing subject you must also consider your other optional subjects. As IL syllabus overlaps syllabus of IR ans US history so it is highly recommended to attempt IL otherwise candidate can choose subject according to aptitude and interest.
I also want to point out one more thing which is IL can be prepared by single book and past papers while Criminology requires study from many books. It also requires a lot of cramming specially law cases, sections etc so, it is not easy for student who does not have background. IL can easily be prepared in almost 15 days time. so, go for IL.

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WA-TU-IZZU MANTASHA; WATU-ZILLU MANTASHA

I am also taking IL, Please suggest me a good book.

International Law by S. K. Kapoor & Tandon is the best book for IL.
If want to consult more than one book go for JWT as it is written according to syllabus.

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WA-TU-IZZU MANTASHA; WATU-ZILLU MANTASHA

Thanks for your comments. This is my first try, so I am completely unaware of books and other study stuff. My optionals are IR, Public Ad, IL, History of USA, Pashto. As only 8 months left for preparation, please suggest me that books which take less time for all my optional and Compulsory as well. Thanking you in anticipation.

Thanks to both Mr Psycho and Madam Anum for your positive response. As I have opted IR, US History so it means IL is mandatory for me.

Yes then IL is best option for you. Good luck.

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WA-TU-IZZU MANTASHA; WATU-ZILLU MANTASHA

8 months are not short. They are more than enough if you do totally dedicated study in these 8 months. Now it is time to study at least 8-12 hours a day to get syllabus covered and to revise it at least twice.
I cannot ask you to follow any 1 specific book as one book is never enough for CSS. It can be a case with a single subject but not for all. I am listing down all books that I am consulting. By these you can get grip on subject.
Optional subjects:
For IL:
1- IL by S.K Kapoor & Tandon
2- IL by JWT for topics according to syllabus
3- Past papers

For US history:
1- US history by Majumdar
2- Sir Naveed Bhutto's notes
3- by JWT
4- Past papers
(I occasionally consult peoples history of US by Howard Zinn)
(1+2 most recommended)

Pashto is not my subject

IR
1- JWT
2- Joshua Goldstien (Most recommended)
3- Parkash Chander
4- Globalization of world's politics
5- Past papers

Public admin
It was my subject in CE-17. I have changed it and I do not recommend to take it as optional. The best book which I have come across yet is Dr. Sultan Khan's book 2017 edition. Also never consult internet for this subject. Questions were in Pakistan's scenario. Not much reliable data is available online. No notes are available. Style of asked questions has been dramatically changed in CE-17. Not a scoring subject after change of syllabus. If you really want to take it as optional buy new book of Dr. Sultan. Solve all past papers. Never go for JWT. It is not good at all. ( I recommend you to switch it with more scoring and safe options)

Compulsory subjects:
CA
1- Dawn
2- JWT magazine
3- CA by JWT (Waseem Riaz Khan)

PA
1- Pak affairs by JWT
2- Pakistan & world affairs by Shamshad Ahmed
3- For latest topics daily dawn
4-JWT magazine

Islamic Studies
I am attempting in Urdu
I am consulting two books
1- Islamic studies by Hafiz Kareemdad Chughatai (Most recommended)
2- Islami Nazria Hayat by Prof Khursheed

English Essay:
Self practice of latest topics+topics in past papers and get them checked by teacher

GS&A
1- Mian Shafique's book by JWT for general science
2- Add more info from internet on book
3- For ability portion check link shared by MrArsalanKhan (moderator) in relevant section

English precis & composition
1- I am following the book by Hafiz Kareem Dad. I have found it best.
2- Plus past papers

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WA-TU-IZZU MANTASHA; WATU-ZILLU MANTASHA

Shall be thankfull if you share ebooks on any online storage web like 4shared.com

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God makes men what they are