Exiting the US on foot at the Mexican border involves no check of any kind of documentation-- you just walk through a couple turnstiles, and a Mexican Marine may search your bag if you look suspicious.
That, of course, makes it easy to be in Tiajuana without a passport. From what I heard when I lived in San Diego, if you bring a US drivers' license, and especially if you also bring a US birth certificate, the border agents may chew you out, but they will let you into the US.
Given this, I wonder what the rationale is for denying felon's passports? I mean, if it doesn't prevent you from leaving the country or entering the country, both of which are violations of international law.
That, of course, makes it easy to be in Tiajuana without a passport. From what I heard when I lived in San Diego, if you bring a US drivers' license, and especially if you also bring a US birth certificate, the border agents may chew you out, but they will let you into the US.