Can't load a JSON file into python

json.loads works on a string. It decodes a JSON encoded string into a Python object. What you have here is a Python object, which you can encode to JSON with json.dumps. Also, there's no variable assignment within JSON. The only thing you can represent is a plain object.

Daniel Roseman is correct. This is not a JSON string. Just make sure to include commas in between each element of the list (you left one out).

variable = [["1","arbitrary string","another arbitrary string"],["2","arbitrary string","another arbitrary string"],["3","arbitrary string","another arbitrary string"],["4","arbitrary string","another arbitrary string"]]

variable
[[u'1', u'arbitrary string', u'another arbitrary string'],
[u'2', u'arbitrary string', u'another arbitrary string'],
[u'3', u'arbitrary string', u'another arbitrary string'],
[u'4', u'arbitrary string', u'another arbitrary string']]

another_variable = "arbitrary string"

another_variable
u'arbitrary string'

The string which you get is not JSON (as claimed before), but partially it could be interpreted as JSON (right part of = statement). You could try to write simple parser to extract what is interesant to you. I had played around and got this:

import json
json_str = """
variable = [["1","arbitrary string","another arbitrary string"],
["2","arbitrary string","another arbitrary string"],
["3","arbitrary string","another arbitrary string"],
["4","arbitrary string","another arbitrary string"]];
another_variable = "arbitrary string";
"""

json_str_list = [js.strip().split("=")[1] for js in json_str.split(";") if js.strip()]
print("=preprocessed: %r" % json_str_list)
print("=json decoded: %r" % [json.loads(js) for js in json_str_list])

output is:

=preprocessed: [' [["1","arbitrary string","another arbitrary string"],\n["2","arbitrary string","another arbitrary string"],\n["3","arbitrary string","another arbitrary string"],\n["4","arbitrary string","another arbitrary string"]]', ' "arbitrary string"']

=json decoded: 
 [
 [[u'1', u'arbitrary string', u'another arbitrary string'], 
 [u'2', u'arbitrary string', u'another arbitrary string'], 
 [u'3', u'arbitrary string', u'another arbitrary string'], 
 [u'4', u'arbitrary string', u'another arbitrary string']], 

 u'arbitrary string']