Is it necessary to soak pinto beans over night before you cook them?

It is NOT necessary to soak any beans before cooking them. It'll just take a little longer to cook them to the softened stage. Many people do 4-8 hr presoaks or "quick soak" for an hour after boiling 2 minutes, but it is definitely not necessary. Some people feel that presoaking then throwing out that water will prevent intestinal problems that some people get, but that isn't even proved for most people. Tossing out presoak water can also lead to less flavor in the bean liquid if it would have been used in soup or stew, etc.

Check out more current thinking on all that from the chef and food scientist Kenji Alt-Lopez (and some before him) starting here:
http://www.seriouseats.com/2014/09/soaking-black-beans-faq.html
(He later did these tests with other kinds of beans with the same results, btw).

Of course, *red kidney beans* should always be cooked at high enough heat to kill a toxin that they contain, regardless of whether they've been presoaked or not.

P.S. I pressure cook my dry beans for the easiest way to do it. Even the densest beans like chickpeas take only a little over one hour from start to finish cooked that way (the pressure cooking part is usually only 30 min + 15 min to come up to pressure + 20 or so for "natural pressure release"--just leaving the lid on till the pressure disspates naturally).

Oh, and never used "pickling spice" in my beans, but the old saw about never adding salt to beans before they're softened has been proved untrue. (Pickling spice is pickling salt, meaning no iodine or anti-caking agents, with whichever herbs/spices/etc a company wants to add.)

It is necessary to soak the beans to ensure they cook properly and in a reasonable amount of time but you do not have to soak them overnight. You can use the quick soak method. Put your picked over pinto beans in a large sauce pan, cover with water by two inches and bring to a boil. Let boil for 1 minute. Turn off the heat and cover the saucepan. Let the beans sit for one hour and then cook them. Do not add salt to the cooking or soaking water as that toughens the beans. I have never tried pickling beans but it would probably be good and taste sort of similar to 3 Bean Salad.

You don't have to soak them, but they cook in less time if they have been soaked.
Also, if you change the water several times while soaking beans, they won't produce as much flatulence in those who eat the beans.

Get a pressure cooker, makes cooking dry beans go a lot faster.

No it is not necessary but it will take longer to cook them if you don't.